USMC Aircraft Tech Question

I am currently 17 and I'm highly thinking about joining the US Marine Corps in a few months straight out of high school as a aircraft technician. Im physically fit but I'm just worried about making a mistake because I've been told by my sister who was a former loadmaster for c130's in the USAF that it's a rough job with long hours. I am mechanically inclined and I work on cars at a tech school so I have a little feel for what would come. I really think that I would be OK with it, but is anybody able to give me some pointers or if it would be a good decision because I'm just really stuck. Thanks!