I (22M) go to a pretty fancy/exclusive gym in my city. I'm an ex-gymnast and fitness is a big part of my life so I spend a bit extra to go to a quieter, nicer gym. I'm there 5 days a week, usually early in the morning or sometimes a bit later on weekends. I usually keep to myself and get in the zone to enjoy my workouts.
A couple months ago I noticed a new woman (34F) had started at the gym. It's small enough that the regulars notice when someone new starts. I'll admit when I first saw her I was full of blood and hormones and thought she was sexy as hell, but being respectful to her space I didn't bother her. As time went on I started sharing a smile with her, or a casual "hi" as we passed by. This eventually turned into small talk if we were using machines near eachother, or more often her asking me for help with new exercises/movements.
It's not uncommon to be cordial, and I often get asked for help by newcomers so I didn't think too much of it and I was happy to oblige. After a time of this our conversations got a little bit more personable and she told me she was married. I'll be honest I was deflated when she said it and I suspect she noticed because she quickly said "yep, now I only get to look not touch, unfortunately".
We grew closer over time, sharing workouts and chatting, and despite all the things I had taught her she seemed to be asking me for help more and more (hindsight ikr). Her outfits changed as well, much to my delight. What started as pretty standard t-shirts and runners shorts turned into lululemon crop tops (I think this is what they are, but to me they may as well be a bra) and the worlds tightest booty shorts.
This is where the story gets NSFW:
One morning I was in very early, to the point where it was just me (this isn't unusual at this time as it's a small gym). A few minutes in she showed up, wearing one of those crop tops that was definitely too small for her (considerable) bust, and a pair of tight leggings with the ribbed/stretched butt fabric. She asked to workout with me and I was more than happy to oblige & enjoy the view.
Our workout quickly devolved into innocent ways to put our hands on eachother. She was rubbing my arms and chest to help me "feel the stretch". I was grabbing her waist during Romanian deadlifts, where of course she thrust her ass right back into my crotch.
We finished our workout, at which point I had an erection harder than any of the barbells, and I was ready to capture this moment as a fond memory for shower time. Then she said she wanted to use the sauna, but didn't want to be in there alone (this actually is a rule incase someone faints) so I said I'd be happy to join her. I took my top off in the change rooms, decided to leave my shorts on (both out of respect and to conceal my hard-on) and went into the sauna. A minute or two went by until she opened the door with a towel wrapped around her.
Before I said anything, she shut the door, turned to me and dropped her towell revealing her busty, mature, fully naked body in all it's glory. If I wasn't already red faced from the heat I was then... She said nothing, climbed over to me and stuck her tounge down my throat. Before I knew it she was straddling me, making out with my shorts off and her hand around my cock.
She rode my cock in that sauna, pushing my face between her big tits while we sweated all over eachother. After about 5 minutes, it got way too hot, so we covertly shuffled into the male showers, found ourselves a private cubical and fucked like rabbits. When I was close to finishing she got on her knees and finished me off with her mouth. I came in her mouth, on her lips and on her face which quickly got washed away by the running water of the shower we had turned on.
We dried off, got changed and shared a goodbye kiss before she said her husband was here to pick her up, and off she went.
Well this has been going on for a few weeks now, and it's been the best sex of my life. We usually do it at the gym, and have come close to been caught a few times now, but that honestly makes it so much more exciting.
Happy to tell you more about it and answer any questions.