Martin Garrix: "I've had club residencies in Vegas over the last couple of years and I always had to stay in my hotel room until someone escorted me to the DJ booth, then had to go straight back to my room as soon as I was finished. I also wasn't allowed to drink or enter the casino parts in the hotel. So now that I'm 21 the whole Vegas experience has changed for the better!"
Chief Keef: "A lot of the guys ain't see 21. It made me just want to do more. More music, more in fashion and start my tech company Digiglo."
Alessia Cara: "There was this weird internal shift that happened when I turned 21 and I can’t explain exactly what it was. It was a series of little moments that made me look at myself and my life more closely. There’s something that happens to you when you realize you can’t run and hide behind your youth anymore. I know I’m still really young but I feel like I’m all the way on the train now."
Austin Mahone: "I think my music is something that's changed over the past couple of years -- I’ve learned so much and been able to develop my sound into something more mature. But I don't think anything specific really changed overnight for me, except now I can buy myself a nice bottle of wine when I want!"
Shamir: "I didn't think it was more possible for me to be more self-aware! After I turned 21, I practiced self care and decided to be healthier. I also learned how to stand up for what's best for me and be more vocal about what I'm thinking and how I feel."
This article originally appeared in the Oct. 7 issue of Billboard.