Injury

Acute injuries, such as muscle strains, are less likely than you might think — and catastrophic weight room injuries are very rare. You can avoid the vast majority of injuries, aches and pains by lifting with good technique and adhering to a strategic progression model. 

However, if you do sustain an injury or flare up an old one, is important to note two things: 

1. Muscles heal relatively quickly, and you will regain all of your old size/strength (and then some) as soon as you get back to training at full capacity. 
2. Injuries will rarely require you to stop training completely. Training through an injury is reckless, but there are almost always ways to safely train around it. You may even be able to perform the same movement that caused of exacerbated the injury — albeit with modified load, tempo and/or ROM.

Don’t be dumb when attempting to recovery from an injury, but being aggressive in your rehab (up to a limit) can facilitate much faster recovery compared to doing nothing.