"Quite frankly, thing weren't great," Rosen tells Men's Health. "I was constantly in and out of appointments with my doctors, and I spent most of my time at home because both physically and emotionally, I felt as if I couldn't go out and do anything. A lot of my relationships took a nosedive because I simply didn't feel up to putting the effort into them."
The problem was that Rosen had thyroid disease, and it was taking a toll on his body in a big way.
"I had barely any muscle mass on me whatsoever, and barely any fat as well," he says. "If I had to guess, I was at about 5-6% body fat with no muscle ... and my hormonal levels were in the gutter. I was incredibly weak, and I was cold all of the time. I felt completely at the mercy of my own body and spent most days hoping my doctors could crack the code to my thyroid."
Finally, they did. Rosen's doctors got him on the right medicine and dosage, and his thyroid was functioning properly at last. The ordeal put Rosen in the right mindset to kick off his muscle-building transformation: "Getting sick and losing my health to things I couldn’t control opened my eyes to the importance of controlling the things we can control," he says.
Rosen was ready to put on mass, so he started reading all the evidence-based health and fitness content he could find—and hitting the gym.
"Once I got a good idea about weight training and nutrition, I started going to the gym and eating a lot," he says. "I 'dirty-bulked' like you wouldn't believe, and just kept eating and lifting and resting. Rinse, repeat." ("Dirty bulking" means taking in a bunch of calories to gain mass, regardless of nutritional value)
He started noticing changes quickly. ("But keep in mind I started from practically zero," he adds.) It felt amazing to be able to climb stairs without getting tired, and to go outside in the summer without wearing a coat.
"Getting stronger and slowly not being able to see my entire bone structure felt amazing," Rosen says. "For the first time in a long time, I felt that I was actually taking control over my own body and not letting my body take control of me."
These days, Rosen lifts five times a week and tracks his macronutrient targets daily. He works a personal trainer now, so he spends his days training clients and doing his own workouts afterward. In total, he's gained 60 pounds—not to mention a six-pack.
Most guys aren't dealing with the same health problems Rosen was, but his advice is relatable to anyone looking to change their bodies: just start, no matter what.
He says, "I know how hard it is to be the guy curling the lightest weights in the gym and barely being able to bench the bar. I know what it's like to feel like you can't wear shorts because you don't want people to see your skinny legs. I am so far from where I started because I started.
"Whether you're underweight or overweight, 23 or 73, I urge you to just begin your journey, because one day those 5-pound weights will be 10-pound weights, and then 50-pound weights, and you'll look back at where you started and wonder why you ever waited to begin."
This article originally appeared on Men's Health