If you have not lifted in awhile or are perhaps unfamiliar with lifting technique, then you may open yourself to injury through improper lifting. One of the main contributing factors to improper lifting is actually attempting to overtrain or excessively lift. If you are trying to squeeze one more rep out of too much weight, you might tighten your neck, stop breathing, hyperextend your arms, and get your back involved in the lift. You might achieve that rep, but anything inadvisable in your lifting form can precipitously increase your risk of hurting yourself. Keeping your back straight, tension out of your neck, and a manageable weight/rep ratio are all critical factors. In addition to adequately educating yourself on the correct way to lift and adhering to these rules, you might consider lifting with a partner to help observe your posture and spot for you during more challenging weight exercises.