"I've had kids that I grew up with, and they're out of the game now," Marisnick said. "They're not playing anymore because of taking steroids and doing that type of stuff."
Marisnick spoke to roughly 50-100 young people about the dangers of PEDs and the benefits of staying active on Wednesday at Minute Maid Park, where the Astros hosted their annual PLAY event, a national public awareness campaign focusing on educating America's youth about living a healthy, active lifestyle.
"It's good to get out here and have a chance to talk to them and tell them what I went through growing up and about the right way to go about things," Marisnick said, "and to stay away from some things that can tear them down in the long run."
The PLAY campaign will host events at all 30 MLB ballparks in 2017.
The two-hour event Wednesday divided the participants into groups. They rotated through multiple stations, beginning with an educational discussion about the dangers of steroids and appearance-enhancing drugs in the Astros' dugout.
"We're just trying to promote the kids and have an active lifestyle, a healthy lifestyle," said Daniel Roberts, an Astros assistant athletic trainer. "We talk to them about nutrition and the use of PEDs and try to get other activities -- not just baseball things -- so they'll have lifelong benefits, not just this one time."
The participants also rotated to an agility station, disc golf games in the Astros' bullpen and a pitching/throwing station led by Astros pitching coach Brent Strom in the outfield at Minute Maid Park.
"It's great. It's not every day they get to come out and hang out on the Major League Baseball field," Roberts said. "That's a cool thing for all of us."
Christian Boutwell is a reporter for MLB.com based in Houston.