Mathematics Major?

Any math majors out there? I've been swapping ma majors around and sort of finally landed on math! I just took a foundations of Mathematics class which was really fun, proofs were surprisingly interesting and even though none of the ones we worked on were too complex they still were somewhat challenging. I'm wondering if the major gets much harder after this? Should I be scared? I was not a huge fan of calculus one but I've been told FOM is pretty much what the higher level courses are going to be like.