Exercise: To ensure you stick to exercise try and find an activity you enjoy doing and rope a friend in to do it with you. This could be walking, swimming, tennis, badminton, table tennis, dancing, bowls, self-defence to name but a few. Get in contact with your local leisure centre and see what they can offer you.
Eating: If you want to change your diet and eat more healthily do it in small steps, that way you are more likely to make long-term sustainable changes. Add a salad to your meal, drink water instead of soft drinks, change pudding to fruit.
Mental wellbeing: Get enough sleep. Set a regular bedtime, avoid caffeine several hours before that time and have a wind down period which could be having a bath or reading a book.
For more details of NHS Self Care Week 2011 and information to help make healthy lifestyle choices please visit NHS Choices.