How do I discipline myself to get back in shape?

Grab a pal. You've already started! identifying and desire are the starting point, and now you have to take the second step. Co-discipline is key. You are accountable to another person to get up and go for that walk, or wog, and before you know it, you see the results. Making a pattern or habit of behavior can jump start your motivation. Replacing a healthy habit for a sedentary habit can be a gateway.