Start low weight, do a few, if it's too easy (your not breathing hard) up it a small amount. When you see ripped guys in the gym a lot of people don't realise they've been gradually building that for years. Your actually tearing the muscle fibres so you need to be careful and do it gradually over time to let them recover. That's how they get bigger, it's like scar tissue forming. That's why you need to eat and sleep as well.