Exercises to help with riding?

You could do squats to strengthen your thigh muscles...keep your back straight and squat down to 90 degrees and hold it for 10 seconds...to this about 15-25 times until it you get used to it and then up it to 30 or so...also to help with posture, put your forearms at 90 degrees against a door frame with your palms against it, and step foreward one step, this will stretch your shoulder muscles back into the position they should be in and it will improve your posture