A Gift

   What sport does he like? If it's football, take a ball or something from your favorite team - a cup, a scarf, a notebook, a T-shirt ...

   Ask a relative or friend secretly

   You can get some dumbbells from a Chinese store if you want it to come out cheaper. Another option is cancer, something related to fitness - a fitness bracelet for counting calorie steps, etc. You can also take a team or rubber bands for training. Sports shoes too or some nice and quality sports t-shirt. Another option could be something like a nice basketball if you play basketball or soccer, depending on the sport you practice. I hope you like the ideas. Success!

   If he goes to the gym and trains hard - wicks are something he may need. Or make a t-shirt for him, for example, if you type "Gym t-shirt design" in Google, you can find an idea that you like. size wears or sweatshirt if he likes to dress sporty.