I’m a recovering people pleaser. Suppressing and repressing my needs, desires, expectations, feelings and opinions used to be as natural to me as breathing. To me, it was normal to tell people what they wanted to hear (read: lie) to make them feel better. Yes, I’ll be there for Christmas. Yes, I’ll do that for you. Yes, I can fit that in. And then I’d seethe with resentment and feelings of self-loathing, even as the Good Person in me knew I had ticked off at least some of the requisite qualities – kind, loving, hardworking and eager to help – that people pleasers hold dear.

Despite being a Good Person, I felt like, well, shit most of the time. It baffled me that while I devoted so much time, energy, effort and emotion to being a Good Girl, I did not feel good about myself. Which is why I never felt I had the right to say no.

I saved the word for 999 occasions only – occasions where my back was against the wall. I was convinced that saying no because you wanted to, whether it was out of necessity, desire, or even obligation, was something other people did – you know, the ones who’d earned that right with their worthiness.

But then, one morning in early August 2005, aged 28, I discovered that I could say no simply because I wanted to. For 18 months prior to that, I’d traipsed in and out of various hospital departments after being diagnosed with a mystery autoimmune system disease (sarcoidosis) that had nearly left me blind in one eye and made me an expert at hiding severe joint pain.

On that particular day, I sat in a consultant’s office in the lung clinic of a north London hospital braced for bad news. “The treatments haven’t worked,” the consultant duly told me, “so you’ll have to go on steroids for the rest of your life to avoid early death.”

As my consultant’s voice slipped into a monotone, it hit me: I’d been sick for at least two years and, while I’d understood that my illness was serious, I’d done whatever doctors had told me, my focus has been on making everything about my condition easier for other people. That’s why, when I heard myself say “no” moments later – resonant, unapologetic and decided – I looked around to see who had said it. Not only “no” but “I want to explore other options.”

Normally I’d feel anxious about saying no to an “authority” and appearing “difficult”. Not that day. Fear of dying aged 40 far outweighed the potential discomfort I usually sensed in others when I so much as contemplated saying no, never mind verbalised it. It hit me that no one was coming to save me. It was my responsibility to make decisions and take care of myself.

The doctor told me I didn’t have any other options. It would have been easy to back down and then spend the next few months or even years stewing over my silencing of myself. Instead, I said, “I hear all of that, but I’m still going to explore other options.”

Eight months later, I was in remission from my incurable disease, had begun radically overhauling every area of my life and was in a new relationship with my now husband. Yes, I did employ some alternative therapies (kinesiology and acupuncture), but it was hearing the term “boundaries” not long after that appointment that changed – and saved – my life. Over the 18 years since that fateful day, time and time again, the solution to almost every struggle and problem has proven to be the same as it was back then: embracing the joy of saying no.

When I said no in the consultant’s office, I hadn’t been in even one healthy romantic relationship. I was in a constant cycle of toxic relationships and family drama, thanks to parental issues stemming from abandonment, criticism and chaos. I was burned out at work and even in some friendships. I hated myself and my life because it felt like nothing I did was ever enough. Even so, in my mind, no led to pain, rejection, failure, disappointment, and abandonment.

Time and again, what I thought was being “good” and “helping out” was people pleasing – using “pleasing” to influence and control how others felt both about themselves and about me. It was a way of gaining their attention, approval, love and validation. It was also a way to avoid conflict, criticism, stress, disappointment, loss, rejection and abandonment. It was a long list, one that people pleasers will recognise in themselves. We often know what we are doing and why – and if we’re not that happy with the why of it all, we keep doing it anyway, allergic as we are to saying no.

Since that first no in the consulting room, I have spent years testing my “no” in situations ranging from the professional to the deeply personal. After years of trying to have a better relationship with my mother, for example, I started saying no to what was on offer in the relationship. It wasn’t enough. I’ve learned the power no holds to connect you with your true self, the self that deserves more. If you don’t say yes authentically, you say it resentfully, fearfully and avoidantly, and that leads to more problems than if you’d just said no in the first place. No doesn’t mean rudeness or rejection, it means being able to connect with people authentically and leads to a richer, healthier, more joyful life.

Overcommitting has been one of my biggest problems. For much of my life I have overcommitted so as not to disappoint or burden others. Nowadays, I embrace saying no to certain work projects as well as to social invitations. I’m being more discerning with my “yes” and finally breaking the habit of cramming my schedule. Recently, after much soul-searching, this has meant saying no to continuing with my eight-year podcast. I’m 46, perimenopausal and knackered. Releasing myself from this commitment has brought me flexibility and more time to relax with my family. It’s given me a newfound feeling of freedom – and some lovely early nights.

Top tips on when and how to say no

Overcommitting People pleasers say yes reflexively, indiscriminately and fearfully, which can result in burnout, illness or spreading yourself too thin. Use no to respect your own wellbeing and priorities. Try saying: “I don’t have the bandwidth at this time” or “I don’t want to say yes and then let you down, so it’s a no this time.”

When you want to stop dating someone It’s tempting to ghost someone, overlook discomfort and red flags, or keep going until a better relationship comes along, but you both deserve more than that. Try saying: “I don’t see this becoming a serious relationship and that’s what I’m looking for right now” or “I’ve enjoyed spending time with you, but as we both want different things, I’m going to end it here.”

Decline the tricky family gathering Being obliged, guilt-tripped or shamed into spending time with family, especially at Christmas or key events, leads to tension and resentment, not connection and harmony. Opt out of the upcoming event altogether or limit your time there. Try saying: “I can’t make it, but have a lovely time” or “This year, we’re doing Christmas at home. How about we come and see you on the 28th?” or “I value spending time with the family, but the fighting is exhausting, and I can’t do that this time.”

Navigating the persistent and pushy When someone keeps pushing when you’ve already said (or hinted at) no, it’s time to be direct. Direct doesn’t mean rude or difficult, it means clear.

Try saying: “I appreciate you taking the time to explain further, but my answer is still no” or “I know in the past I’ve backed down and gone along with what you want, but I won’t be doing that on this occasion.”

Dealing with unsolicited advice or invasive help Well-meaning loved ones bombarding you with advice, not trusting you to know what’s best for yourself, or transferring their fears on to you, can make you feel guilty, overwhelmed, and unheard. Try saying: “I appreciate your concern, but this is something I need to figure out on my own” or “I know you’re trying to help, but I don’t need you to [whatever they’re doing or suggesting].”

The Joy of Saying No by Natalie Lue is published by Harper Horizon at £11.99. Buy it for £10.55 from guardianbookshop.com