The world hasn't seen a whole lot of Rob Kardashian recently. The brother to Kim, Khloe, Kourtney, Kendall, and Kylie has been laying low ever since a spate of rumors cropped up about his supposed substance abuse problems. His mom refuted these allegations last spring, saying any claims that Rob, 28, was checking into rehab were "completely fabricated." But it's clear that her son has been going through something, especially after Khloe shared that her brother was "definitely not at his happiest place that he once was." That's why it was especially nice to see the reality star looking fit and relaxed on his Instagram account recently. Sunday evening, Rob shared a black and white selfie: He's looking healthy and notably slimmer than the time he was captured publicly on camera. Apparently the workouts he's doing with his big sister Kim are paying off. Between her regimen and Khloe's budding fitness career, Rob has plenty of supportive resources behind him. It's not always easy shaping up, but it looks as though this Kardashian is on the right track. We're wishing him all the best!