Need advice or support?

So I've been feeling really low lately. I've just been stressing out about everything. I'm supposed to go into the Navy in December, but I can't keep thinking about if I fail boot camp and what a disappointment I'll be to my friends and family. My mental health isn't the best and I'm afraid it will also get in the way of me doing great. If I wasn't going into the navy I'd have no other plan for my life. I just feel like I have no control.