If you help me I'll 'make it worth your while'. [=I'll make it worthwhile for you; I'll reward you for helping me]
Seeing my children's joy made building the tree house all 'worthwhile'.
The money is for a 'worthwhile' cause/charity.
(..) Oh, God, this could be very unpleasant. Ay ! Bugger, bugger. Now what in the world in this garden could make that ordeal worthwhile ? Nice garden. ""For June who loved this garden. From Joseph who always sat beside her.'' Some people do spend their whole lives together. (..)1999 Notting Hill