I have a special mounting block my brother built me, modeled after the one that we use at the assisted riding program. It is kind of a "chute". I ride rescue horses and a lot of them wiggle around when mounted- so they can walk into the chute, I climb up 4 steps and there is a 4x4 foot platform on top. Swing a leg over and there ya go. They can't move back or forth and get away from me LOL!!!
The other side of the chute is made of railroad ties, 2 ties dug into the ground as uprights, one going across. I can use it as a hitching rail and it is very handy!