Often when we begin a difficult journey the hardest steps we take are the first ones. If we can just start and tell yourself take a couple steps (I'll walk around the block once,workout for 10 min) and once you start you will find I feel better and more motivated to even more.
Remember there are two pains in life. The pain of disipline or the pain of regret. The pain of disipline is short term. The pain of regret can last a lifetime.