I cannot for the life of me keep my legs where they are supposed to go while I ride! I'll get em perfect then there they go, sliding forward and forward and forward. I think it might have something to do with my leg strength, so any tips for keeping my legs back and toes in or strengthening exercises?
Ride without stirrups or bareback with your toes pointed up. Have someone watch you and yell at you whenever your legs go back or toes go down. Do lots of walking and trotting, and if you can, canter too. Do patterns and transitions, to help improve your balance and muscle.
Use an exercise bike or bicycle, making sure the seat is a bit high and your heels are down.
Walk your neighborhood or on a treadmill. For 10 steps every few minutes, let your legs go back as far as they can, until you can really feel a stretch at your upper thigh/pelvis area, before bringing your leg forward again. Shoulders up and back, lower back relaxed (NOT arched), and don't over-stretch. You want to just feel it.
When you're in the saddle with stirrups, do NOT brace your leg against the stirrup. You want to relax your heel straight down. Picture your legs like deep tree roots, reaching down to the dirt. Another visualization is thinking about your legs being filled with ice cream and it melting and dripping straight down the back of your heel. Feel your leg weight relax, relax, relax straight down through your heel. Feel your hip open up, so your leg hangs straight down from your pelvis.