You enjoy the work you’re supposed to do for your concentration
This should perhaps be a “duh,” but it can be fairly easy to ignore this preference when you’re juggling other concentrations based on say, future prosperity. I’m an econ major because I really enjoyed doing the problem sets in Ec 10 (and fancy that, Ec classes have a fair amount of problem sets). I am not a math concentrator because I absolutely dreaded each problem set. I am not a philosophy concentrator (despite really liking philosophy) because I couldn’t imagine myself writing philosophy papers for the rest of my time here.
My math concentrator friends generally really enjoy their math problem sets. My CPB friend really enjoyed orgo. My history concentrator friend would happily check out a 2 foot stack of books from the library whenever she had to write a paper.
Pay attention to your mood when you’re doing homework. If you’re happily reading about linguistics or happily writing papers about social norms, then you probably know already what would be a major that would make you happy.
It’s super easy to be interested in many, many subjects (and enjoy lectures on many of said subjects), but chances are, you probably actually enjoy doing the work in just a few of them.
That’s all folks!