verb To serve oneself, especially to take food or other supplies, rather than wait to be served by another; used to indicate friendly permission or invitation.
If you want to take a shower, help yourself to towels; they're in the linen closet.
verb To take something freely; to serve oneself without restraint.
He said I could help myself to the chocolates.
verb To exhibit self-control.
Sorry for eating all the chocolates - I couldn't help myself.
verb Used other than figuratively or idiomatically: see help.