Your metabolism is partially affected by your level of physical activity. Performing regular cardio helps in two ways. First it burns calories whilst performing your cardio and secondly, the amount of calories burnt following a cardio workout will remain higher for a few hours after. So, going for a run, walk, bike ride or some rowing a few times each week will burn more calories and boost your metabolism!!
A pound of muscle burns around 6 calories per day whereas a pound of fat only burns around 2 calories a day. Therefore by increasing your lean muscle mass you will increase the amount of calories you burn at rest.
Drink plenty of water
If you are not properly hydrated then your body may not be able to function as well as it could. This will lead to a reduction in the amount of calories you burn. To maximise your metabolism you will need to drink enough water, especially when you are training.
Caffeine and Alcohol
Caffeine and alcohol dehydrate the body therefore lowering your BMR (amount of calories burnt at rest). Where possible substitute for a glass of water, and this will again maximise your metabolism!!