Lunges aren't bad for your knees.....BAD lunges are bad for your knees.

Welcome back!
 One comment I hear a lot which is completely unacceptable (in my little world) is "I can't do that movement, it hurts my (fill in the blank)." Now I understand the implications of an irreversible injury (i.e. complete cartilage breakdown), but barring that, there is absolutely no reason why any movement/joint should ever hurt, twinge, ache, etc. If the movement is done in the intended (and available) range of motion for that joint, and done with appropriate mechanics, it should be pain free, and will be efficient as well. In fact, the very movements you avoid because they "worry" you are the same owns we should probably be focused on! Now, some days we may not be able to go through full range of motion, but we should be asking the most range we can safely out of our joints each day, and working on our mobility so that we don't seize up like an unoiled tin-man when we are 35!

"I can't do a full squat, it hurts my joints."

"Yeah, me either. We should stick with movements for people our age."

And coming back to the cartilage breakdown (or some other form of debilitating chronic injury). Unless you were born with a hereditary predisposition for the problem (not "my father and his father and his father were all carpenters, so we all have bad backs", I'm talking deep, internal hardwiring malfunctions!), there's a really good chance that poor movement got that person into the problem in the first place. But is it too late? NO! Our bodies were put together to last 100+ years, and do so well. Poor movement each and every day takes away years (like running the car with no oil). The longer you do it, the more damage that can occur. But put some oil in that car now, and it can run a whole lot longer! You owe it to yourself to move well, to learn to move well, because you move every day. You might as well learn  to do it the right way! And I promise, every movement you make has a "right way" and a WHOLE bunch of "wrong ways". Walking, running, bending, sitting, standing, jumping, hopping, stair-climbing, ladder-climbing, mountain-climbing, laying, lunging, sitting up, turning over, picking something up, and putting something down. Don't know how to move well? Read a book, watch some videos, or do the best thing you can do, hire someone who spends their entire life studying movement. When your car needs improved, you take it to a mechanic. When your body needs improved, you see someone like me. So after you drop that machine of yours off at the Body Shop (...really Lucas? Pathetic pun), remember to keep doing one thing for me.
 

Stay Fit.

Your body BEFORE good movement.

Your body AFTER good movement. (Man, you look goooood, I bet you deep squat, don't you?)