Justin Bieber is hitting the gym again, and he's not shy about it.

Late Thursday night, Bieber posted on his Instagram account a collage of photos of him working out without his shirt on. In one photo, we see him curling a 40 lb. weight and in others, we see him doing various other exercises, presumably pull-ups and crunches.

"Back in the gym #dontbescared #orangegymrats," he writes in the caption.

Given the kind of week Bieber has had, it's no surprise that he's burning off stress at the gym. The 20-year-old was recently reunited with on-again, off-again girlfriend Selena Gomez. Earlier this week, Bieber was involved in a car accident when his Cadillac Escalade collided with a BMW. He was also named in a lawsuit when he struck a pedestrian in June 2013 while trying to escape paparazzi with his Ferrari.

See More Pics of Justin Bieber + Other Shirtless Male Celebs

More From Hot 975