I'm a sophomore Physics major, and I'm looking for a solid Calculus review. I've taken classes on Single and Multivariable Calculus before, but the classes didn't push that hard, and the problems in the book (Hughes-Hallett) are all a breeze. I'm looking for something that I can teach myself with and hone my Calculus skills. I've considered Spivak, but some people say that the added rigor is not all that useful for physicists. I'm interested in doing proofs, but mostly proofs related to physical phenomenon and the equations that describe them, not proofs of the basic properties of integrals and such. (Actually, I'm very interested in both, but physics is my priority right now. I would love to come back to the other stuff later). But maybe I'm wrong about Spivak. I haven't looked at it yet. I'm just worried it would be too much of a sidetrack from physics right now. If I'm wrong, I'd be glad to try it. But I do want a book that challenges me. I've only had the basic freshman calculus courses, and I'm starting to realize how little they've prepared me. I can do every problem in my Calculus book in at most a couple minutes, which seems a bit silly. I think it speaks poorly to the exercises rather than highly of my skills.