Why do you want to get fit?

So you want to get fit. But do you know why? You're likely to have a general idea. Perhaps it's because you want to change the way you look – to lose weight and to look more athletic. Or maybe it's because you want to change the way you feel – to be more energetic and confident. It may be that you've been told that you need to get fit for your health, or that there's an increasing sense of urgency to keep up with those around you. Whatever it is that drives you, motivation matters.

And it matters a lot, because your willingness to engage with exercise will only ever be as strong as that motivation. Interestingly, research has shown that we are far more likely to follow through with our resolutions if they have a so-called intrinsic motivation. This means having goals that are meaningful to ourselves, as opposed to goals that are designed to please or impress others. Writing down the answers to the following questions may just help clarify your motivation.

1 What do you think the results of exercising your body and mind will be?

2 How much do you value these results?

3 How do you feel about doing it (confident, embarrassed, frightened, determined)?

4 What do others think about it, and do they influence you?

5 How easy do you think it will be to regularly train the body and mind for a short time?

6 How much control do you have over your ability to make that happen?

Setting realistic goals

When it comes to committing to a sustainable and enjoyable training programme (whether for the mind or the body), it's all about setting realistic goals.

Working towards a goal is just as important to wellbeing as the attainment of the goal itself, so make sure you focus on the journey as much as the destination, and remember that both the body and mind take time to change.

In a 2009 study at the Health Behaviour Research Centre at University College London (UCL), scientists found that it takes an average of 66 days for a new behaviour pattern to become part of our regular routine. They also discovered that the more you follow the "same time, same place" philosophy, the more likely you'll continue with that behaviour. So give yourself time to adapt to each phase of your new exercise plan, and be confident that the changes are sustainable. This way your goals will always be realistic.

As much as you can, think "little and often". So rather than signing up for the marathon to train the body, or booking a ticket for a Himalayan adventure to train the mind, focus on quality rather than quantity. As Dr Elena Antonova, a neuroscientist at King's College London, says: "The brain is plastic and has the ability to rewire itself depending on our experience.

"As we learn a new skill, mental or physical, neurons are rewiring themselves, with old pathways being weakened and new ones being formed. The rapidity of these changes is dependent not only on the duration of practice, but also on the regularity and quality of practice."

A balanced approach

Picture for a moment the face of Usain Bolt as he crosses the finishing line of the 100 metres final in the last Olympic games, or Lionel Messi nonchalantly dancing his way through the defence of an opposing football team. They make it look so easy, right?

While we may not aspire to that level of performance, we can still learn a valuable lesson from these athletes. When we exercise we need to apply just the right mental balance. This means a sense of committed focus on one hand, and relaxed ease on the other. We need to carry out the exercises with a sense of flow and naturalness, rather than a forced aggression or stiffness. This way, not only does the workout feel more enjoyable, but it will also be more sustainable. It will improve your form, rhythm and, ultimately, your results, whether training body or mind.

Talking of balance, never underestimate the importance of rest in an exercise programme – of both body and mind. In a recent study at the University of Kent, researchers found that when cyclists rested their mind before competition, as opposed to being involved in some kind of cognitive task, their endurance improved by 15% – simply by resting the mind and thinking less beforehand.

How to train your mind

So, how do we go about training the mind to be committed and focused on the exercise, while feeling relaxed, and generating a sense of ease and efficiency in the body at the same time? Well, most sports scientists seem to agree that it begins with learning to be more self-aware. This means rather than being caught up in lots of thinking, we develop the ability to step back from it all, to have a greater sense of clarity and space in the mind. As mentioned earlier, the technique usually prescribed for this is known as mindfulness. But like any technique, it requires practice and familiarity.

And that's where meditation comes in. Forget any ideas you might have about monasteries or Indian ashrams, because meditation is simply a technique that allows you to train in mindfulness, to become familiar with what it means to be in the present moment, undistracted by thought, and operating at your full potential. And you don't have to travel to Asia to do that. In fact, you can do it just as well in your bedroom. You then have to apply this newfound sense of calm and clarity, of mindfulness or awareness, to activities in everyday life – in this case, specifically to exercise. So, just as an athlete intensively trains his or her physical muscles in a gym to become stronger on the pitch or the athletics field, so the brain requires these short periods of intensive training, of meditation, for use in everyday life.

Of course, the great thing about training the mind for sport in this way is that you'll be training it for everything else in life at the same time. Research from Harvard University shows that when we engage the mind with awareness, or mindfulness, we invoke what's known as the relaxation response. Contrary to how it may sound, this is not a sleepy condition, but a surprisingly alert and efficient physiological state. This is in sharp contrast to the stress response, which most of us are more familiar with, and which limits both our physical and mental capabilities. And who wouldn't want less stress and more relaxation in their life?

• Andy Puddicombe is a co-founder of Headspace