Join Date: Dec 2010
Location: southern Arizona
Some horses are easier than others. Some have a big push going thru their back that lifts you up, and all you have to do is pause at the top & then gently come down. OTOH, a lot of western horses will do an easy jog...slower, and there isn't much lift at all. My mare does it that way naturally - feels good to ride while sitting, but it makes posting hard.
I wouldn't worry about diagonals for the first few lessons.
Also, I think of it more as rolling up & forward onto my thighs than an up-down motion with stirrups. Personally, I like a discrete post. I want my crotch and rump off the saddle, but my jeans still touching...at least, that is the mental picture I use. If you are an inch out of the saddle or 6 inches, either way the weight is off the rump.
Finally, some saddles make it tough. When the heels are forward of your hips, you have a tendency to thrust your hips forward to get over the stirrups so you can 'stand in the stirrups'. If you have shoulder - hip -heel in a vertical line when seated, it makes posting easier. With time, you will learn to use your thighs instead of standing up in the stirrups.
Riding a horse is very different from normal daily activities. I ran/jogged for 40 years before I started riding. Instead of making riding easier, it made it harder. The muscles that tighten up from running need to be loose to ride well, and vice versa. You could be a top athlete in many sports and still be totally out of shape for riding. That is one of the things I like about riding. It is a great complement to running because the muscles used are different.
"Make the right thing easy and the wrong thing...well, ignore it mostly."