Anything that's different from your own realm of experience as a human being whether it's driving a car or a boat or using guns anything that separates you from yourself and leads you more towards this character's existence is a big help.
If you've got a big gut and you start doing sit-ups you are going to get bigger because you build up the muscle. You've got to get rid of that fat! How do you get rid of fat? By changing your diet.
