Several things that have worked for me.

1) Exercise, a lot. Put it first, so that you'll actually do it.

2) Eat right. These things, exercise and food, can have a far greater impact on your work than you might realize.

3) Discipline. Show up and put the time in. Force yourself.

4) Pomodoro technique. Commit to yourself that you'll put in 2 solid 45 minute periods per day. Work your way up from there. You need to do it even when you don't feel like it.

5) Get friends who encourage you to be your best. If you don't have friends like that, contact me unoti2@gmail.com