LPGA golfer Lexi Thompson is showing off her guns -- and a little more -- on the May fitness issue of Golf Digest.

So how does she get those biceps? She boxes, of course.

"I don't do weighted machines," Thompson told the mag. "There's no sense in a golfer risking putting that much stress on the joints."

"Punching teaches you to get power with your whole body," she adds. "And it gets the anger out. Like the golf course, you can get in your own little world where nothing matters."

Thompson also shares why when weekend hackers like you hit the golf course, you are terrible.

It is because you are weak.

"I basically live standing on a Bosu ball," she says, referring to the inflatable, unstable, hemispherical platform. "Exercises like this help build the strength so you can swing within yourself. A lot of amateurs over-swing because they're not strong enough to stay in control."

Thompson joins Holly Sonders (2013) and Paulina Gretzky (2014) as female cover subjects for the magazine's annual fitness issue.

S/He Said: Millennial slang words REVEALED