I don't have time

Probably the most widely used excuse for not doing any exercise. You don't need to have hours on end to take action, or put your life on hold to make exercise work for you.

Work out earlier in the day: studies have shown that people who are new to exercise and choose to do it first thing in the morning are 75% more likely still to be exercising 12 months later.

Schedule in exercise blocks at the start of each week, and write reminders everywhere - your computer screen, diary, mobile phone and Post-It notes on the fridge - to let you know when you should be exercising.

Think shorter exercise bouts, too: research has shown that people who take shorter exercise bouts end up completing more than those whose exercise bouts are longer (International Journal Of Obesity, 1995). Seek out ways to exercise at home. People tend to stick with home-based exercises more than facility-based exercise sessions (Perri et al, 1997).

I can't be bothered

Many people perceive exercise as a skill, requiring great physical coordination or an aptitude for sport, but this needn't be the case. Use home exercise DVDs, or try walking routes of differing lengths. Stop looking at exercise purely as a way of getting hot and sweaty, or as something that has to be done in full kit. Building up lifestyle activity to top up your structured exercise can help change your traditional perceptions about exercise.

I don't have any support

Social support is very important, be it from a partner, friend or group. There will be people, however, who actively discourage your new healthy habits. Identify who will be the supporters and saboteurs. Studies with recovering heart disease patients reveal that men had an 80% adherence rate to their exercise programme when supported by their spouse, compared with just 40% when their spouse had a neutral attitude. Find exercise partners who will be powerful motivational supporters. Find people who can help make it easier to build exercise into your life - for example, if your partner or a friend picks up the children three days a week, you can use that time to exercise. Explain to others the importance to you of following your exercise programme: it may help them to be more supportive.

I lack self-esteem

Don't wait for your self-confidence suddenly to appear once you've lost weight. Invest in it now. Teach yourself small successes. Take 120 micro-bouts of 15 seconds' exercise throughout the day, and you've done 30 minutes of exercise without even realising it. Congratulate yourself with Post-It reminders each time you complete your actions.

There are too many obstacles

Hindrances such as having to work late or not being near a gym can act as barriers to exercise.

Honestly identify your behaviour patterns. These are the chains of events that can stop you from exercising. For example, you may have planned to go to the gym after work, but you ended up not going because your boss shoved a report under your nose as you were walking out of the door and said they wanted it ready first thing the next day. You may blame your lack of gym attendance on your boss, but in fact the real reason could be because you overslept, which put pressure on your day from the start.

I don't know how

You want to get fit but don't know where to start, what plan to follow, what exercise to do or what food to eat. A lack of knowledge can be just as confusing as having too much information. Make a commitment to learning about how your body works and the impact your actions, however small, can have on it.

I travel too much

Being away from your normal environment can be an exercise killer. Your routine is shot to pieces, you mainly eat out, you may have to decipher different food cultures and, of course, you're just plain tired.

Pack your pedometer. You may not feel like exercising as soon as you arrive at your destination, but do try to move your body - resolve to get 4,000 steps on that pedometer as soon as possible. It's a great way to explore, and it'll help you get rid of travel fatigue. If you are on a business trip and your structured exercise sessions are just not going to happen, resolve to get in your daily 10,000 steps - even if it means getting up a little earlier.

· This is an edited extract from The Weight-Loss Bible: The Definitive Guide To Total Weight Loss And Wellbeing, by Joanna Hall, published by Kyle Cathie at £19.99. To order a copy for £18.99, including mainland UK p&p, call 0870 836 0875 (theguardian.com/bookshop).