Sometimes you work as hard as you can on something, and it doesn’t work out. The question is: How do you know when to give up? I usually tough it out longer than most people would in a similar situation – which is why I often succeed where others have failed. I also know that sometimes you have to throw in the towel. Maybe you failed, but you probably learned something valuable. Chalk it up to experience, don’t take it personally, and go find your next challenge! By: Donald Trump