Squats and leg workouts. Just look online for good leg workouts and there are even rider workouts that give an outline of what you should do everyday. I follow one along with running and it has really helped my a quotation.
I have the same problem and it's because my ankles aren't flexible so I find myself tipping forward. Check your hip and shoulder alignment and what I do for my ankles is sometimes I stand in a doorway and put my heels down.