1) You have to poop right before your workout. NOT because you had coffee, but because you're SCARED. You've heard "If it doesn't scare you, you're not lifting heavy enough", right? That is fact.
That doesn't mean you should lift recklessly or with shitty form. If you have access to a spotter or you see a dude at the gym resting/texting between sets, grab 'em and have them available to offer assistance SHOULD.YOU.NEED.IT.
2) You need a nap. You're exhausted, tired, fatigued...but NOT in a way that makes you feel like shit. In a way that tells you that you put your body through the wringer in the RIGHT WAY. You stressed it. You tested it. You said to your body: "Don't be a little bitch. You've got this!"
3) You're hungry. You did damage. The RIGHT kind of damage, and your energy needs to be restored. Your metabolism is doing its job by reminding you that it NEEDS fuel to recover and get your muscles and nervous system ready to lift heavy shit again. HEAVIER shit.
4) The weights that used to intimidate you now seem a bit small. When you pick them up, they practically get air because they feel so much lighter than they used to.
5) After lifting, everything in life is just easier. You've lifted the weight of the world ALREADY; nothing the day or the people you encounter can throw at you can touch you. They won't want to anyway...you walk with confidence, with your head held high, like the bad ass you are.
So if someone asks you (i.e. ME) if you're REALLY lifting heavy; will you HONESTLY be able to answer "YES!"????