Being 3-bet isn't the end of the world. 4-betting light is one way to counter it but it's not the most important adjustment you should make. The most important adjustment is to not open as wide when you're 3-bet a lot. The second most important adjustment is opening up your value 4-betting range. If you open wide in late position and you get 3-bet a lot, consider being willing to get it in with TT+, AK (or even 88+. AQ, however, is only for your value range when you're dealing with a maniac; it's much much weaker than most people think). Only in third place of importance comes 4-betting light (that is, as a bluff where you fold if the other guy shoves).
Second, besides adjusting your ranges, make your button raises smaller (minraise or 2.5x) when you have a wide 3-bettor in the blinds. My range for opening when I'm "tightening up" on the button is
That's about a third of all hands. When he 3-bets me, I'll be 4-betting him a little more than 10% of the time with the intention of getting it in, I'll be flatting him about as often (with, say, 99-88,AQs-AJs,KQs,QJs,AQo) and you can widen your flatting range a little bit more if his c-bet% is very high.
You'll still lose money when you get 3-bet, but that's unavoidable. Or rather, it's not unavoidable (because you could tighten up to a point where he'll lose money from 3-betting you), but the money you make from stealing wide when they just fold is still greater than the money you lose when you get 3-bet. If that makes sense.