I've been riding for almost 33 years, and for the last 23 of them I've used a mounting block. I had a bad riding wreck when I was 30, and it tore all the muscles in my lower back and pelvic region. Because of that, I can't lift either of my legs high enough to mount from the ground.
There's absolutely no shame in using a mounting block, and as Michelle stated, it's actually easier on the horse's back if you use one because you're not wrenching them to the side every time you mount.
In fact, as soon as I show up with mine, almost everyone in my riding group asks to use it.
Also, don't be afraid if you fall off or need to get off your horse at some point during your ride. I found that rocks, downed tree branches, stumps, etc. work great for giving you just enough leverage to get back in the saddle.