The 48-year-old actor-director, who suffered a massive heart attack back in February, revealed on Instagram that he is back down to his high school weight.
"The scale said 198 today! This is the first time since High School that I’ve weighed under 200 pounds!" Smith captioned a pic of himself hiking with his dog. "Never... NEVER imagined I could get here again but a heart attack can be a great motivator."
Despite all the motivation in the world, Smith knows he didn't make it to this milestone alone; he went on to thank many people for his incredible success.
"This #wwambassador thanks @ww - whose Points system made it possible to drop the lbs! I also wanna thank my little exercise partner Shecky, my Vegan explorer @harleyquinnsmith, @veggiegrill, #pennjillette, @adam_rifkin, @raycronise and #runyoncanyon!" he wrote. "And a big thanks to all you folks who kept me going with your sweet supportive sentiments!"
Smith finished his inspirational post with a note that he's not done working on himself just yet. "Now over the next few months, I’m gonna slowly try to get down to 190!" he promised.
The exciting news comes just a few months after Smith told ET that he thought he'd always be overweight.
"I just assumed I'd be fat my whole life and I'd never see my high school weight again or any of those things," Smith said at the time. "I'm 47 years old, so that was all in my rear view. But after the heart attack, suddenly I was like, all right, I never want to be back in that room again with someone going up my groin to get to my heart through my femoral artery, telling me that there is a 20 percent chance that I will live, and 80 percent chance I'll die."
Watch the video below for more of ET's sit-down with Smith: