Exercise is something that you need every day. Try to build it into your life.

It doesn't just burn off the calories (though it does that too).

It makes your mind sharper.

It makes you feel less tired! Try it if you don't believe me - when you get home from work and just want to be a couch potato because you had a tough day, instead walk around the block and enjoy the gardens and trees and birds etc. When you get back home, don't you feel better?

Also it helps you to have better quality sleep. Which means that you feel better the next day and can achieve more with ease.