Katie kept walking, pushing through her tween years. She got taller and thinner as the last of her baby fat drained out. As she finally hit her teen years at 13, she felt a tingle in her chest. She looked down to see that her nipples were making slight indentations in her tank top. As she walked, her nipples rubbed against her tank top more, feeling more sensitive as they did. The areas around them started getting more puffy as tissue began forming. "I'm growing boobies," said Katie, her mind expanding to explain what puberty is. The discomfort faded as a training bra appeared under her tank top, comfortably cradling her nascent breasts.
The beginning of puberty spurred Katie to walk even more, wondering how big she was going to get. As she continued through her teen years, she gained more height. Her legs became more shapely as her thighs and hips start filling out. She could feel her butt growing into a more appealing shape. Her tank top pulled up more, showing her belly button. Her training bra became a proper bra as her breasts expanded, putting her into the upper B's. Katie's face got prettier as her lips became fuller and her face started losing its roundness. Her hair grew longer before a band put it into a ponytail. At 16, Katie was becoming a looker and she knew it. "Sweet sixteen and ready to drive," she said proudly, her voice not sounding as high-pitched as before.
16 looked good, but there wasn't quite enough freedom for Katie. She pushed onward, going through the last of her high school years. She gained a little more height as her legs grew even more shapely. She could feel her hips and rear growing out to a childbearing form and a tingle through her groin told her she was fully ready to have children of her own. Her tank top fully slid up to reveal her flat stomach as it merged with her bra to become a sports bra. Her breasts swelled up to C cups as her cleavage became more displayed. Lipstick and earrings appeared as she pushed past what would have been her high school graduation. "I'm a legal adult," said Katie proudly, her voice dropping into a lovely tenor. At 18, she was now free to pursue adult interests.
18 may be the age where adult access is unlocked, but 21 is where the fun really starts. Katie pushed herself to reach that. Puberty had a last few gifts to give to her before it finished. Another two inches of height finished her growth. Her butt, no, her ass was now a perfect peach that any guy would look at. Though plenty of them would also be watching her tits especially as they swelled into the D class. Wilder thoughts entered Katie's mind as new possibilities open. "I'm going to party hard tonight," said the 21-year-old college girl.
Though Katie was a fully grown woman with a sexy figure, something intrigued her. After all her walking, her muscles weren't nearly as big as she expected them to be. She was hardly out of shape, but she would have thought all her walking would be reflected more. "Let's see if I can work on that," she said as she kept walking. As she walked, she gained more memories of fitness courses and knowledge about physical regiments. The changes soon became noticeable. Her shapely legs grew more toned as the years of walking became physically present. Her arms also thickened as years of workouts were added on. Her exposed midriff rippled before her abs pushed out, becoming more defined until a hard six-pack was formed. Katie felt a rush of power as she became a female bodybuilder at 25.
Feeling that it is enough, she hit the stop button and the treadmill stopped itself, ending her journey of growing up. Getting off the machine, she looked to herself and was amazing by the end result. What was once an 8-year-old innocent girl has bloomed to become a college graduate with a body of a young amazon.
Flexing her arm, she smirked and said, "Check me out. I have become quite the babe. I bet my big sis would be jealous with a body like mine."
Then a thought occurred to her. She called her own mother a big sister without giving it some thought. Then she realized why. See, her mother, Kellie, gave birth to Katie at 22 as a drunken one night stand with a random guy led to her getting pregnant in the first place. But now that Katie is 25, it means that she wasn't the daughter anymore, but a little sister to Kellie.
Katie, having to figure that part out, sighed and said, "Guess that means that Kel got the sister she wanted, but to my expense of me using the treadmill cabinet to age myself up." But a smile crept up her face and she said, "Oh well... It doesn't matter anymore as I and now a fully functional and hot adult. Didn't have to worry about going through school since I grew out of it in minutes. Now I can do whatever I want and with this body, I show it off in front of some hunks."
Walking away from the cabinet and exiting the arcade, she was ready to take on the world. But what to do to celebrate her new life?