A day at the gym

I happen to weigh myself today and weighing machine shows 50 kg. For a petite 5 foot me, 50 kg is a not a complimentary weight. An hour after a light lunch, I decided to hit the gym.
The small gym in my area was rather empty. A gray-haired man in his fifties was running on a treadmill and I picked the treadmill next to his for my workout. I turn on the machine and started with a jog. The sound of the man's treading footsteps boosted my energy to keep up my pace. I hasten my pace to keep up with him, and soon, our footsteps were in sync.
After 20 minutes, I was so worn out that. I wanted to stop, but pride stopped me from doing so because I, a nineteen year old, did not want so seem so unfit to a man with gray hair. I keep on pushing for another 15 minutes and at last, the man stopped, wiped his sweat, and stretched out in front of the mirror. As soon as he left the gym, I hit the stop button immediately, collapsing on a bench.
I was already fast asleep by 9 pm that night. It was one of the best sleep I ever had, and one of the worst body ache I experience the next morning.