Two words: Rachel Star.
Seriously, though... you have more leverage if you are using your feet for support, and are crouched, in an athletic stance (this is why it's called an athletic stance, after all).
So, for example, if he's on a low chair, and you can crouch over him while standing, this will give you the most power, and you should be able to last the longest in this position. It would be easier to crouch over him in reverse cowgirl, of course.
If you can't stand, the next best thing is to kneel, using your knees as support, but, this is not quite as powerful as standing.
The only way to get better is to exercise, practice... What's making you tired? Are you running out of breath, or are your hips locking up? For the former, you need arobic exercise, for the latter, you need to do strength-building exercises, like lunges, hip thrusts, and even squats (which is just a great all-around exercise).
alternate between using your legs to slide yourself up and down and your hips. This will give your muscles time to recover. Also try basically laying (chest to chest) and thrusting back and forth (rather than up and down) to switch it up as this calls for stomach muscles rather than your legs or hips. Variety can work wonders when you find yourself over-exhausting a single muscle group.
Scroll Down to Read Other Opinions
What's Your Opinion? Sign Up Now!No pun intended - Eat a banana. Hell, eat two. The fruit is high in potassium which will let you're muscles work longer with out cramping. It also wouldn't hurt to do do a thigh stretch regularly. Hope this helps, have fun ; )
being good at this position from what I understand (being a guy I've never actually tried to do it myself) requires a tremendous amount of leg strength and stamina--the kind you build up thru activities such as gymnastics, dance, or just plain working out. there are ways you can "cheat" but by using those techniques you're decreasing the quality of the experience for both you and the guy
Come on. No one can help you with a physical insufficiency. If you're not in tip top shape, forget about it. Sorry, but it's the cold hard truth.
Sexual Relationships 
Sexual Health 
Most Helpful Guys