When you hit the gym when you are younger, and most likely more supple you can get away with a lot more. Sloppy form will not kill you, unless you try to deadlift or squat 600 lbs and you only weigh 110! Recovery is also much faster, you can hit the gym 5 days in a row with generally low consequences, except general muscle soreness.
As you age into your thirties and beyond muscle soreness can be the warning signs of injuries and too little recovery between training sessions. If you regularly experience persistent discomfort in the lower back for instance its time to back off. What you need is a new training approach and mindset. You need to open your mind to workout advice that is based on science and appropriate for your age.
No one is asking you to retire from the gym. In fact here is no reason beyond serious injury that you should not be able to work out up until senior age. I for one plan to work out right until the end of my old age, unless life has different plans for me. But the will is still there, if you know what I mean.
So why is everyone intent on pushing it to the bone each time they hit the gym. Half of it is based on ego, and the other half on getting the wrong advices as Arnold would say. Going crazy and attacking the weights or the treadmill each time you hit the gym is a recipe for disaster. Some of the smartest athletes you will find in the gym are competitive powerlifters. Not the guys who take loads of steroids and blow up to 350 lbs and go heavy, heavy, heavy all the time. They only work their max lifts once or twice per year, and rarely work close to their maximum lifts.
No one has a body that can cope with this. Just look at Ronnie Coleman now for instance. When he was 350 lb and looking absolutely massive and squatting 8-900 lb and yelling light weight baby he looked indestructible. Now there is nothing wrong with lifting heavy. Its just that you cant do it all the time. Today Coleman needs multiple hip, and knee replacements, he is also a shell of his former self.
Dorian Yates won the coveted Mr Olympia title 6 times. He trained heavy all the time. Now he does not have any life delimiting injuries like Ronnie Coleman, but he is famed for saying he wished he had of stepped back the heavy weights a touch and cycled the intensity. He means he should have trained heavy for a while then deloaded the weight to say 50% and increase the reps. Then he would build back up and go heavy for a few weeks.
Dorian was famous for being the most intense guy in the gym ever, and it shows in his incredible physique. But he would have liked to have a longer career at the top, and he feels he would have got that if he backed off the extreme training all the time. That would have increased his longevity in the sport. Sound advice.