My biggest failings have been 1) not listening to my body, and 2) not following a structured program.
If you combine the two you wind up with someone who is always pushing his limits, suppressing pain and ultimately injuring himself.
When younger I could afford to play with injury because my recovery was relatively quick. As I got older my injuries became more frequent and they grew more severe.
When I was younger my program basically consisted of adding an arbitrary amount of weight whenever I could. There was no structure, no periodization, no protocol for what I should do if I failed a lift. If I had a good day and peaked for a lift I didn’t understand why I couldn’t repeat that performance next week and would struggle against it. I basically trained at or above my maximum all the time, which is bound to produce injuries.
Now that I’m older and I have access to way better information via the internet I find reputable programs and follow them. They provide me with a sensible progression, limits, and what I should do when I eventually peak and regress.
Train both smarter and harder, preferably in that order.