It can be very difficult to 'make haste slowly' when something is damaged or hurt and needs time to get better. When you get older you know the clock is ticking, and you have an unspecified amount of ticks left. Therefore you get impatient
When you're eighteen, and believe you're indestructible, it's easy to tell yourself 'It's only pain," and work through it. At that age everything heals faster anyway, even if you try to sabotage the natural process by skimping on recovery time.
About fifty years down the line not only do some of the pigeons come home to roost, they gleefully crap in your head.