Swoon!

Justin Bieber left Hailey Baldwin at home and went on a solo hike at Runyon Canyon in LA this afternoon, and he worked up such a sweat on the trails, he stripped his shirt off when he got to the top!

The "Sorry" crooner had a very Leonardo DiCaprio in Titanic moment as he stood on the edge of the cliff, arms outstretched with his eyes closed. Was he praying? Suntanning? Soaking up the moment? Either way, he gave us a nice long glimpse at his rock hard tatted torso, and for that we're thankful.

We're not a big fan of his new shaved head, but it doesn't look quite as bad when it's covered up with a hat.

JB has been highly emotional lately, and our photographers tell us it seemed like he had a lot on his mind.

    "Justin seemed deep in thought as he hiked. When he made it to the top, he was just looking out over all of LA and soaking it in, but there was a sadness to him. He seems very lost."

He might be going through some stuff, but he's still sexy!