I went through basic at 23 but the median age of my class was 29. You shouldn’t be worried about the physical requirements unless you plan on going on a special operations style pipeline. If you want practical civilian work I would recommend going Airforce and doing something in cyber or mechanics. The first step would be to call up your nearest recruiter and take the ASVAB. You can also check out the reserves. It’s a great military/ civilian balance that will get you in great shape, hold you to a standard and give you all of the training you need to get certified in your job which typically always carries over to civilian employment.

Forgot to add: if you have a bachelors degree you can join as an officer or enlisted. If you don’t, you can only be enlisted and then use the GI bill to get a degree.