In my 30's I was working out regularly at a nationally known gym, I'll leave out the name as to not draw attention to the adult activities that took place within.
The locker room was a series of three bays. There was a door just after the third bay that led to the sauna and shower areas. I would usually choose a locker in the third bay as it gave the best view of the men going into and out of the shower area.
The sauna was a small room with a glass door. As it was dark in the sauna you could not see inside from the well lighted bathrooms directly across from the sauna. This was an ideal setup as you could see someone approaching in plenty of time.
The sauna itself consisted of two tiers, a lower and upper bench in a "L" shape. It was fairly easy to spot guys who wanted to show off or play, they would typically be nude with just a towel wrapped around them. When they sat on the benches they would let their towels fall open to reveal their cocks.
One day after my workout I stripped down, wrapped a towel around my waist and headed towards the sauna. On the upper bench, just outside of sight of the door, sat an older man.
He was in his mid-fifties, lean, and completely bald. He had small wisps of greyish hair on his chest, and was covered by only a towel. I did not recall seeing him in the gym before, but he was very attractive. My penis jumped excitedly under my towel.
I took a spot on the upper bench as well at the opposite end of the bench. We were the only two in the sauna at that time.
I glanced over a few times and saw him rubbing his cock through the towel. He noticed me looking at him, and his eyes caught mine. He asked me if I would like a closer look. Too stunned to speak I could only nod my head yes.
He unwrapped his cock from the towel exposing his magnificent member. It was nearly seven inches long, and had a nice thickness. His head was glistening with precum, he had obviously been enjoying himself before I arrived.
He gripped his shaft in his hand and began stroking it up and down as I stared transfixed on his beautiful glistening head. I dropped my towel to expose my stiff erection. Seeing my now nude body caused him to rub faster.
I was enjoying the show when someone approached the door. We both quickly covered ourselves before the door opened.
A short overweight man walked in. He had a big belly, and I recognized him as a regular. I often saw him glancing at men in the locker room and showers. The bald gentleman must have also recognized him as he quickly removed his towels and resumed stroking his cock.