I have one trick/suggestion that gives you a little more propulsion.
1. stand at the horse's front shoulder, facing his rear.
2. grab the iron, and twist it toward you.
3. grab mane with your left hand, and put your left foot in the stirrup (http://www.newrider.com/Starting_Out/Getting_On/mounting3-250.jpg image on the first 3 steps).
4. finally, hop on your right foot and swing it straight in front of you and over the saddle.
This method gives you some more hmph in your mounting.
I would like to say that although I can get on a horse like that, I try not to do it a lot. I have found that it can stretch the leather on that side of the saddle. Plus it is more pleasant for you and the horse if you use a mounting block/step.
I am fortunate to ride at a place that has therapeutic riding. So there is a ramp and step combo mounting area that allows you to sit straight on the horse with just about no jumping up required. I have found that the pony I ride likes it a lot better when I get on that way...what horse wouldn't---1. human soars up on your back and plops all X weight on you hard, or 2. human daintily/slowly steps over and sits on your back. Also, I am only 5'3". So, depending on the size of the horse, it can be quite a chore to do that.
Don't let it get to you. I think it's part of the movement of the last 32 years---there is no shame in stepping on things to get onto the horse. Humans, horses, and stirrup leathers usually prefer it.
In the meantime, if it is really killing you, try the above, facing toward the rear method & swinging the leg forward, up and around. Good luck!