Jennifer Lopez turned 46 on Friday, and even after a daytime celebration she still had the energy to slip into a super sexy cutout dress and party it up at 1oak in Southampton. Hot damn! We hope WE look like this when we're in our mid-forties!

J. Lo was accompanied by beau Casper Smart, and she spent most of the night partying with pals French Montana, Thalia, Fat Joe and his wife Lorena. The birthday girl didn't post any photos with Casper, but the backup dancer did post a selfie on Instagram on Thursday expressing his excitement for the festivities the following day.

While J. Lo has always looked incredible, it seems like she's only getting better with age. How is this possible?! For starters, she's very disciplined with her diet and exercise, and she says she rarely drinks alcohol. And even when she doesn't feel like working out, she makes herself go to the gym.

"[I'm like] a fighter, going into the ring. I do my cardio and I do my workouts with the Tracy Anderson Method," Jennifer said in an interview earlier this year with Redbook. "Sometimes when I get home and I'm not feeling so great, I make myself go to the gym. Then I come home and take a shower, put on a great outfit, some makeup, tie my hair up, and I feel pepped up and great about myself."

It definitely shows!