Ever since retiring from the NBA, Kobe Bryant has taken on a big brother role to younger players in the league. On August 24, a day after his 39th birthday, Kobe took to social media to issue challenges to some young stars in the sports and entertainment world.

Using the hashtag #MambaMentality, Bryant challenged Isaiah Thomas to make the All-NBA First Team following his trade to the Cleveland Cavaliers. He also challenged DeMar DeRozan of the Toronto Raptors to rekindle a friendship with someone he lost contact with from his childhood.

Kobe’s challenges did not stop at NBA players, however. The Black Mamba also issued challenges to Kendrick Lamar, Olympic track-and-field sprinter Allyson Felix and Richard Sherman of the Seattle Seahawks.

“I challenge your record label to revolutionize the music program at Centennial High School #MambaMentality,” he tweeted to Kendrick Lamar.

Check out Kendrick Lamar’s other charitable deeds.