How do I know?

innocenceportrayed

Without going to a gym or having a personal trainer, how do I know i'm exercising correctly? I've read books and watched videos but when it comes down to it, I can't see what I'm doing so I don't know if I'm correctly doing it, like a pushup. I refuse to do it with knees down or crossed, I do a mens style pushup, but I don't know if my back is flat, it doesn't feel arched and I'm not in pain afterwards, but....

Also, is it normal to get dizzy after a workout? I've always had a problem that I get dizzy and at first I thought I just wasn't taking in enough water but now I know that's not it. Especially after a run, I get very lightheaded and dizzy. I'm not usually feeling like I'll vomit, just everything else uncomfortable.

Any advice would help, thanks.