If you feel that you already had enough and you can't go anymore... then it's not for you, just quit and go home tell your mom that you give your best, it wasn't just for you. Your mom will listen to you, he will dry your tears and pamper you. But what does it mean? can it change anything?
Pursuing something big is painful, sometimes it is really making your body and mind quit but that's they way it is. You need to make sacrifices to get big things.
Remember that pain doesn't count. It doesn't matter how many battles have made you suffer, it doesn't matter how many wounds have left scars into your body. Pain doesn't count, all that counts is success. All that counts is the results that you are making everyday. Success doesn't care if you're wounded and cannot breathe anymore. So don't ever make dramas that you're so tired and you can't go anymore. I know you are hurting but those hurts, those whining and bitching can't give you anything.
Never count your pain, just keep moving, only count your success and progress.
If you're hurt, if you're tired then rest but don't talk about it, don't make dramas because that shit won't help you. It is only weakening your mind, it only means you are weak and you want to get sympathy from other people. You're still alive so what are you complaining about.
Successful people doesn't make excuses, they don't talk about their injuries, traumatic problems, adversities etc. They don't talk any of them, they were so focus on taking actions and making results. They were so focused on making a progress even if that progress is too little.
So stop making dramas and start executing your game plan. Don't have a self pity, make yourself angry, make yourself motivated and driven.