Main thing I learned with health and fitness is that, for me, I was always trying to do right long enough so I could cheat and "reward" myself. And that always lead to failure. I had to change my mindset from, "Be good until you feel like you can be bad" to ,"You've adopted a new lifestyle. This is you now. You're not building up points so you can buy a whole pizza and 3 beers. You're doing this because this is you now. This is the reward, being able to run miles in the heat. Right now, sweat all over you, breath going in and out. This is the reward." For some reason that worked for me.