People and there behavior.

 It is like you can give give give and people will take take take but when you need something they don't know you or they can't help you for some excuse of a reason. You can go around giving the shirt off your back but when you need something look around and see who is there for you. 

If you were a few dollars short who would give it to you or who would give you a sad excuse? If you were in the hospital who would actually come see you? You got to look around your friend group and make sure they are for you and not only there for what they can get. 

You can give a person an inch and try to help them out but they will end up taking a mile and keep taking until you have nothing or they can't take anymore. So be careful helping and make sure they are not taking advantage of you and it is definitely okay to say no and putting your needs and wants up front before them.