. ♪ baby baby baby >> reporter: over the years we've watched justin grow up, from that babyfaced kiddabbled in drugs and alcohol, raced fast cars, he went a little too far into his own celebrity. >> reporter: the more mature bieber decided last year to take a break, reflect on his career, canceling his "purpose" tour, saying on instagram, i want my career to be sustainable but i also want my mind, heart, and soul to be sustainable so that i can be the man i want to be, the husband i eventually want to be. his decision to slow down may have been influenced by this man, the so-called pastor to the stars, karl lentz. my "nightline" coanchor byron pitts asked pastor karl about justin's decision to cancel his tour. >> he told me what he's going to do. he spoke on his own behalf about it better than i could. i like it when people make decisions for their soul first. career, money, platform, stature second. >> reporter: the hipster mega hit "chill song" has included the likes of kylie and kendall jenner, selena gomez, and bieber's own fiancee hailey baldwin. >> he invested energy working on

. >>> the chef, the babyfaced assassin, and now the professor? warriors star steph curry stacking up the accolades and nicknameses. the two-time mvp and three-time nba champion is introducing a new master class where he will teach you the secrets of his craft. i wonder if chris paul is going to sign up. curry's class comes with a work book and 17 video lessons. you can see all of professor curry's teachings for only $90, but here is a sneak peek. >> we overload ourselves in the workout with two basketballs or a tennis ball. it makes the game seem a lot slower and you're able to process things a lot better. that's why we're here, to get better. to maximize the quickest release possible for you, lock in on the path that the ball takes from your catch ready position to your final release point soft that's how you can shoot the same from whether it's in the paint all the way out to the d 3 area and knock it down. i'm stephen curry, and that is my master class. >> this is great. great stuff. take the class. we'll be in the nba soon, i assume. >> it co