She originally took the invitation to train with him as a simple friendly gesture. He actually brought it up several times, while she began working out on her own, before she accepted his offer to work-out together. She desired him, yes, but did not think that the feeling was really mutual. Even if it were, she did not feel that either of them would do anything. She went to be polite, since she had little else to do.
It was a private gym, so they were alone. Once there, he became so friendly, his flirtatiousness could not be denied. In addition, he was charming. But, surprised and unsure of what to do, she simply went through the motions of the workout. Before she had realized what was going on, he was saying that they were done for the day and he needed to be getting home. She regretted not being more forward, immediately asking if she could join him at his next session. He brightened and agreed.
She altered her clothing then, wearing tight running pants and a thin cotton shirt that clung to her breasts. Most importantly, instead of a sports bra, she wore a sexy, latex one that allowed her nipples to poke through. Rubbing against her shirt, they were readily visible the entire night. He was almost unable to take his eyes off her C-cups with their nipples jutting out like buttons. She was thrilled, and so aroused that she could feel the moisture in her crotch.
After that she worked out with him regularly, their flirtations charging her sex life. She was so excited, physically and emotionally, to have found someone that wanted her and that she wanted in return. She knew she was on dangerous ground; that they might fall off the edge. Yet, the uncertainty of that, in and of itself, was so enthralling that she could not let it go. She wondered only when and how it would end.
****
As their workouts became more frequent, the chemistry, the sexual tension between them, grew. Every time he saw her, working out or not, his blood ran to his crotch and his hormones went into overdrive. She released in him a pure animalistic urge to take her and show her what a man he was, what a lover he could be, that was only barely contained. He wondered if it wasn't blatantly apparent. It certainly would be to anyone who looked at his crotch. The bulge she created in the front of his pants was unmistakable lusting for her.
While they had started working out wearing plenty of clothing, at least enough to have been considered decent even in public, he noticed, with a carnal thankfulness, that they were becoming more revealing. He thought of the planning that he now put into his outfits. Each day before going to work he would try on his work-out clothes, trying to find what showed more of his body than the day before. Though he could not be sure, from what he saw, she was doing the same.
They weren't wearing less, at least they hadn't at first. It had only been a change from baggy old clothes to tighter newer ones. Their clothing then became tighter still, hugging more of their bodies, showing the other more of their physiques. He loved wearing the tight sweat pants, almost painted to his body. They showed her exactly how big of a package was waiting to be unwrapped. Even more so when, after exercising, the pants slid into his ass crack. This tightened the front of them to the point that not only did his underwear line show, but each testicle was held separately. It was almost as if, just by looking, she could cup one in each hand, holding them apart from his throbbing erection, which she gazed at more and more often.
At first he had simply worn tighter sweat pants. Then one day she had seemed to absent-mindedly spill her drink on his shirt, and for lack of something more comfortable, he had simply removed it. As they exercised that night, she looked more and more often at his chest and arms, especially as they developed a glistening coat of sweat. He was thankful that his body had regained form quickly, as her passion became more evident in her eyes. He remarked how comfortable he was, being cooler and without the tugging restrictions of a shirt. She suggested that he just go without from then on, but the smile on her face told him they were becoming more daring, more openly sexual.
Their next workout, he took of his shirt before they started working out. She surprised him by doing the same, standing in only a sports bra a size or two too small, and the shortest spandex shorts he'd ever seen. They were so tight he could see the lips of her vagina through the curvature of the fabric. He was so aroused that his cock pulsed the entire work out and he could hardly exercise.
