Thor thinks being a hero is all about bashing monsters. It's a lot more complicated than that, as he learns.
Sacrifice for him means giving up everything for the benefit of others. Loki make sacrifices too, though they're more of the knight-takes-pawn types than anything he has to do. Jane and her buddies make sacrifices by pursuing the leads on a scientific phenomenon that no one else believes in. Even Odin has to make sacrifices with his Odinsleep.
If you want to be a player in this game, you got to give…and not because of what it gets you, but just because it feels good.
Questions About Sacrifice
What, specifically does Thor sacrifice to his greater goals and why?
What kinds of sacrifices do the people of Asgard have to make for the safety of their kingdom.
Do villains like Laufey and Loki make sacrifices? To what end?
How does the spiritual nature of the characters' sacrifices reflect in the outside world?
Chew on This
Sacrifice in the movie only counts if the characters have no alternative gain from it. (Like Loki, for instance.)
Sacrifice matters no matter what the losses and gains are, provided that it's undertaken with a sense of selflessness.