Any behavioural psychologist will tell you the underlying reason is simple: people keep on trying to change their behaviour (the effect) and not the cause of it.
Let's face it, have you ever found it harder to lose weight after losing it once before? I know I have. That's because you know dieting means reprogramming your taste buds, reducing your alcohol and cutting down on your intake of fat and sugar.
It would be a lot easier if these foods weren't so addictive. It seems easier to do something about it later, rather than today.
But eventually, if you're one of the lucky ones, something changes. The very thing you have been putting off has triggered a change of heart; you end up doing it.
What changed? Well go back to the behaviourist and the opinion would be "you got to the end of your rope". In other words, you changed what you linked pain and pleasure to. Not taking action became more painful than doing something about it.
This is called "emotional breakthrough", according to Anthony Robbins, bestselling author of Unlimited Power.
"It's what drives all of us to motivation, to take on new actions that ultimately get us to experience new results," says Robbins.
It's what we experience with our gym members daily.
It's not so much the change in behaviour that's important, but rather getting to a place where you've just had enough and where the status quo is no longer acceptable.
Okay, so let's start getting motivated right now. Here are five strategies borrowed from Anthony Robbins:
1. Decide on the very thing you desire but find the hardest to get motivated to do.
2. Answer the question: Why haven't you done anything about it? What pain do you think you may have linked to not taking action?
3. Determine the pleasure you've had in the past by indulging in the thing you want to change. Identifying these pleasures will help you find new pleasures without the negative consequences, such as the thought of looking good and feeling strong versus supersizing yourself with two chocolate brownies, washed down with a large hot chocolate.
4. Determine what it will cost you if you don't change now - avoiding the beach, having the satisfaction of buying new clothes and positive self-esteem.
5. The final step is to write down all the pleasure you will receive taking each of these actions now.
Good luck. It won't be easy but I can guarantee one thing - it will certainly motivate you.
• Peter Rana is the founder of BodyTech Gym.