Don't ever be the yes man or woman. In any situation. Not at work, in relationships, or even when deciding what to eat. Ok, that's a bit extreme but you get what I mean. If you always say yes and agree/do everything, you can be sure that someone, somewhere out there will take advantage of you. Sure, at work you're very capable and always get things done regardless of deadlines they throw at you. So you're a superstar, huh. But that's the problem. They'll just keep throwing more at you because they can and you've been fine handling it this whole time. I'm not saying to say no to everything, but make sure you're not always saying yes at your own expense.

Have toxic friends/SO who just leech and cause unhappiness? Cut them from your life. Life too short to be with people who make you unhappy. Just say no (and good riddance).