[MLeake]

I understand about physical limitations, even though I'm only in my early 40s.

That's partly because, in my early 20s, I had an impact with a wall in a racquetball court (of all things) that herniated two lumbar disks, one so badly that it impinged my left sciatic nerve to the point my left leg was barely useable. It ultimately required surgery (diskectomy). Every so often, since then, I've tweaked the old injury. Sciatica isn't fun.

Along the way, I've knocked one kneecap 7 or 8 degrees out of alignment (dropped a 55lb dumbbell on it), but that was fixed over time via physical therapy. I tore up the soft tissue in one shoulder doing too many dips, then damaged the other shoulder by favoring the first one....

Also tore the junction of my left achilles and gastrocnemius in a football game... That one talks to me if I run much more than a mile.

So, given that list of limitations, I've had to modify my routine.

Squats went away after the back injury. There's really no way to do those without loading up the lumbar region. I'll do leg presses on a seated shuttle, but no squats. I have to be very careful with shrugs and curls.

I also learned that doing more core work is good for supporting the back. Planks in particular, but also crunches, leg lifts, etc. A stronger core section means less back pain, in any given activity.

With the shoulders, I figured out what range of motion I can work before I start feeling pain. If I push those limits, it isn't with weights, it's with yoga or plyometric exercises.

For many people, yoga or tai chi make a lot more sense than resistance training. For people with leg injuries, Pilates was developed to help rehabilitate ballet dancers with leg injuries, so it's typically a good fit.

For arthritic knees, aside from glucosamine, I don't know much about dealing with that. Although if I had those issues, and lived near a lake or river, I think I'd do a lot more canoeing.

One of the big things I've found over the years is that if I don't enjoy an exercise, I won't do it. It's much easier to motivate myself to go to the dojo than it is to get myself to go running. It's much easier to motivate myself to get on a mountain bike trail than it is to get myself to ride a stationary bike. In the winter, I like skiing. Hiking with the dogs is a good option.

So, to summarize, tailor your workout plan around your limitations; find exercise programs that you actually enjoy, whenever possible. And a point I should have raised earlier - consult your physician for advice.