Real sorry to hear that dude, hope you feel better soon! You really gotta be careful and practice safe lifting techniques. I'm 19 and I also work on cars and diesel trucks and so far I've been doing ok in avoiding problems.
One thing I learned early is always, no matter what it is, if its over 30 pounds and its on the floor you have to lift it with your legs. Try to avoid bending over to pick up most things, keeping your back straight and crouching down is always easier on the back. At least mine