I'm 52, married to an OTR trucker, with my 3 grown kids, daughter 30, her 10 yo son, and sons 25 & 24 living with us. Each is his/her own special problem, but with my husband's (Mike) help, I can deal with them. He came up with what he calls the "Axiom of Parent", and it goes like this...
"God and parents help those who help themselves."
When you're young, you can ask us for something, and if we have the money, we feel you deserve it, and it's not out of line, we'll try to say yes. After 18, you're on your own. We've tried to teach you to do for yourselves. If it's real important, and you've tried everything in your power to do it yourself, then we'll help as best we can. But we're not going to give up what we need or want for you. 18 years of that is enough. And with that help will come respect earned by trying to handle it yourself first.
I think that last line did more to get our kids off their butts and do for themselves than anything.