There are some mid-market gyms where you’re discouraged from bringing your own towels. This prevents people like me sullying their uniform fluffy whiteness with my own grubby rag, plus the customer doesn’t have to worry about dragging a soggy towel back home. Wins all round – except, of course, if you’re fat. I work out, swim, jump in the shower and grab the complimentary towel to walk to the changing room, only to discover it covers just over one boob’s worth of my modesty – and that’s just not enough boob.

Like lots of people, I want to be fitter. Exercise has been part of the rollercoaster ride of weight gain and loss I’ve been on since I was a child. When I was 20, I lost five stone in a year by allowing myself only 1,000 calories a day (excluding gin) and walking off 700 of them. My adult relationship with food and fitness didn’t really get off to the healthiest of starts.

Now I’m 35 and overweight. I want to fall in love with exercise, but I’ve struggled. I keep trying new things. I keep trying old things, including the gym. But the message is clear: they haven’t considered the needs of someone over a size 14. It’s almost as if they don’t care about attracting a chubby clientele, which makes no sense: surely large people are exactly the sort of people who should feel welcome.

I asked an expert: why don’t gyms go for the fat pound? “Ultimately, it costs more money,” Nicola Addison, owner of Eqvvs Training, told me. “It costs more for the facilities to employ staff with the right skill set for that clientele; it requires more in-house training.”

You could say in-house training was what was missing when my friend Gemma asked about a powerlifting competition at her local gym, but I’d go with basic empathy. Gemma is 32, size 18, and hoping to get pregnant soon, so she’s spent the last couple of years working hard to lose weight and build strength. She has shed five stone. Her favourite fitness activity is powerlifting, but at her gym the free weights are on a separate floor to the cardio equipment, next to the men’s changing room. “It’s intimidating,” she says. “Very rarely is there even a woman on that floor.” When Gemma picked up a form for a powerlifting competition, “Two staff from the gym came over and took it out of my hand. They didn’t say anything. I said, ‘Can I have an application?’ and they just laughed.”

Gymtimidation is real, and it’s not just the business model or ignorant staff – it’s the culture. It’s the weights being on a different floor, or in a separate room (annoying). It’s the skimpy towels (fattist). It’s the posters of smiley, young, slim, able-bodied white people on the cross trainers.

After spending most of my 20s joining and breaking up with various gyms, last year I decided to become more adventurous. I started with running, getting up at 6am and throwing myself round a park. I downloaded all the free apps, such as the NHS’s Couch To 5K and Runkeeper, and got vaguely competitive with friends online; I bought LCD Soundsystem’s running album, 45:33. I liked running, but never loved it, so when I dislocated my kneecap in an unrelated accident, I was relieved to give it a miss.

Next, I tried the Lifesum app. You tap in your weight, age, gender and how much you want to lose over how long, and it tells you how much you can eat. For me, that’s 1,498 calories, or 9.5 Daim bars. I know that because Lifesum works out the calories in any food and exercise, meaning you can offset a post-pub pizza by cramming in five hours of night cycling. It’s basic “burn what you eat” stuff, but the constant monitoring only reminded me of the obsessive, unhealthy food/exercise relationship of my 20s. So I started searching for my next fad.

There are lots of things I secretly think I’ll be a natural at, given the chance: parkour, being a secret agent and street dancing are just three. After five years of saying I was going to go to a dance class last year I finally signed up. There are lots of things to be mildly anxious about when you join a community street dance class, in east London, as a 35-year-old, plus-size, white woman. I had imagined the room would be full of 17-year-old Lil Bucks, popping their joints before I’d even got my sports bra adjusted. But when I looked in the mirrored wall, I realised how wrong I was. I wasn’t the oldest or the only big girl in there.

I came home afterwards and did the Funky Penguin for my boyfriend in the kitchen. I learned our class routine to Uptown Funk and did it in bars and at parties, to the delight and horror of my friends. It turned out I’m not that good at street dancing. So it was on to the next sporting challenge.

Kitesurfing is where you stand on a board, on the ocean, in a strong gale and strap yourself to a kite. I saw a video on YouTube of people who could jump all the way over Worthing Pier, propelled only by the power of their kite. It’s amazing. So I rang and told the man who answered I’d like to try it. As I’m a good swimmer, I should be fine just turning up, he said. And no problem, they have all the kit. We were getting to the end of the conversation and I knew I had to ask the question I’d been dreading. “With the wetsuits, er, what size do they go up to? Because, er, I’m quite big and…” He fell silent.

I can’t remember much about the rest of the conversation, but I know he fumbled, something about how I could try a man’s suit and I should be fine. I agreed cheerfully, laughed, put the phone down and never went kitesurfing. My days of rummaging in a box of clothes that are too small and walking into a group of people looking like a clingfilmed sausage ended at school PE lessons.

I wasn’t exactly comfortable walking into Nicola Addison’s gym in posh west London, either, but I was lucky enough to get a free taster session earlier this year. After my adventures in alternative fitness, I felt it was time to go back to a gym. But was this the right one for me? Addison has trained Elle “the Body” Macpherson, after all.

The session began with a chat about my goals. “I want to be able to run for a bus without choking on my boobs,” I told her, adding that I didn’t want to lose weight by hating myself for being fat, and I definitely didn’t want to yoyo. “I’d rather stay fat than lose weight and put it on again,” I said. She was calm, like a no-nonsense Brown Owl dealing with a hysterical, 17-stone Brownie. “The fittest people are those who are always physically doing things” she said. “Digging the garden, walking the dog, getting off the bus a stop early.” I don’t have a dog, or a garden, but I do take buses. This (I’m calling it Bus Fitness) could be my thing.

“You need to do sweaty exercise for only 30 minutes three times a week,” Addison continued, taking me through a personalised plan. Crawls, stretches, subtle combinations of balance and weight holding. Sweaty, but unexpectedly easy.

Addison emailed me the plan, because I’d probably never be able to afford to go there again, but I can’t help wishing her holistic, motivational expertise was available to people without Macpherson’s budget – bus people. Addison is evangelical about fitness being accessible: “These days, there are so many things. My mum lives in a sleepy village in Leicestershire, and she’s going to Pilates and Zumba in little church halls.”

One barrier preventing non-whippets from working out is simple: the clothes. Sanna Lory works for XL.Promodoro, a new plus-size brand that goes up to a size 26 for women and 5XL for men. “Everyone wants to get fit,” she says. Sanna, who is not plus-size herself, believes many brands still don’t stock big sizes, because “they’re going for an aspirational marketing strategy where they want people to look at their models and think, ‘Wow, they look great, I want to look like them.’” Some people will respond well to that strategy, but many will be put off “because it makes them afraid, it makes them feel judged”.

Aggressive and outdated marketing strategies deter lots of people – fat, thin, old, young, different races, different classes – from trying out new sports, which is one reason Sport England made an almighty intervention at the beginning of 2015, with its #ThisGirlCan campaign. “It’s interesting, because when we went into this, we thought there might be different barriers, according to what size you were,” Tanya Joseph, the campaign’s director, tells me. “We actually found that the barriers are pretty universal.” Joseph and her team discovered three common barriers for women: appearance, ability and priorities.

The campaign’s aim is to get more women exercising, and it started with a TV advert that showed people with different body types doing exercise. Already it has had an impact. “Normally it takes a really long time before you start seeing people taking action,” Joseph says, “but we’ve already seen a 6% growth in people in our target groups being active, which equates to over half a million women.” She tells me about a new Sport England scheme, an element of which encourages leisure centres to put hooks by the pool for towels, so that anyone who feels self-conscious about walking half naked and wet in public can take a towel. “These are relatively simple changes that make women feel more comfortable.”

Many of us, fat and thin, have grown up feeling as if we don’t fit in at the gym. The friendliest grandmother ever could nail down some old bikes to a church hall floor, call it Basic Spin and loads of people would still find it intimidating. But we do belong. If we can buy the ticket, find the time, get through the door, we deserve to be there as much as the next (skinny) person. When I turn up to my first kitesurfing class in the very near future, I’ll be sure to make fitting me in their problem.