I joined a gym in Federal Way recently.

The main reason: I wasn’t happy with how I was looking in my mid-30s, and I wanted to get in better shape. I wanted to be able to play with my kids without requiring knee-replacement surgery. I also have trouble letting go of the past, and still think and act like I’m 21 years old.

But I had ulterior motives for inking my new gym membership. I love to people watch, and there is no better place to watch people than your local gym. Every sub-section of Americana is represented inside the weight room.

The rich and the poor, the fat and the skinny, the strong and the weak and the young and the old. The gym is the great melting pot our forefathers talked about before signing the Constitution.

At first, my goal was to get in and out of the gym as fast as possible. Complete my workout with my iPod fastened to my ears so nobody would talk to me.

But that was before I stopped and realized the true enjoyment that could be had people-watching at the gym. For some reason, it just seems like a breeding ground for tools, knobs and dorks.

My favorite, however, is the dude that I like to call “Mr. Gym.” This is the guy that walks around like he owns the place. He’s usually in his 20s, but I’ve seen a couple of rare “Mr. Gyms” as old as 50-something.

“Mr. Gym” loves drawing attention to himself and will do just about anything to accomplish that goal. He always has his iPod turned up a little too loud so everybody can hear the “anger rock” blaring from his headphones as he walks by. He also grunts like he’s having a baby with every lift. And when “Mr. Gym” finishes a set, he always announces it by banging the weights onto the ground.

“Mr. Gym” also has subtler ways of drawing attention to himself. He employs strategies like having a perfectly bronze tan in February, bleaching the tips of his hair and never wearing shirt sleeves, even outside. I’ve also noticed that “Mr. Gym” usually drives a Jeep Wrangler without doors and spends his weeknights playing softball.

But “Mr. Gym” is far from the only oddity that struts around the weightroom. Your local gym blooms a rainbow of weirdos every hour of the day.

Some of my other favorites include:

• “Creepy Old Man” is the retired guy who was actually “Mr. Gym” back in the 1950s and will tell you stories about how he used to bench press with Jack LaLanne. It’s cool that he’s still working out, but he still thinks its the 1950s and wears a headband, polyester sweatsuit and rocks a Walkman with a Frank Sinatra cassette tape.

• “Overweight Sweater” is just in the gym attempting to get into shape, which is admirable. But please bring a towel, or maybe a pressure washer, to wipe down the elliptical machine after you sweat all over it.

• “The Marathoner” could either be a man or woman who runs super fast on the treadmill and wears shorts that don’t leave much to the imagination. They also wear a T-shirt from a different marathon every day of the week just to prove a point that they are runners. Sometimes I even see “The Marathoner” fake like they are grabbing a cup of water from a volunteer on the side of the road.

• “Miss Gym” is the very attractive young lady that wears next to nothing. Obviously, she knows she is attractive, but wants everybody else in the gym to know the same thing. Everybody in the gym is super nice to her ­— imagine that.

• “Too Comfortable Naked Locker Room Dude” is just that. Obviously, I know I’m in a locker room and people are going to be showering, etc. Not that big of a deal. I’m an adult. But this guy is way too comfortable in the buff and will actually try to engage me in a conversation about the Mariners or the weather while naked. Not cool, naked dude.

• “Mr. Glory Days” is a guy that used to supposedly dominate on the high school football field and has to tell everybody about his exploits. I mean everybody. A simple question like, “Are you done with this machine?” leads to him talking about his 1,000-yard senior season and the unfortunate injury that squashed a certain NFL career.

• “Fake Personal Trainer” might be as annoying as “Mr. Gym.” This is the guy that rolls around and attempts to give you tips on lifting weights even though he looks like John Goodman. It doesn’t matter if you are a complete stranger, “Fake Personal Trainer” will show you the correct way to do a biceps curl.

So, thank you gym. I can’t wait to go work out tonight and see if I can spot a few more weirdos.