I personally loved my breadth/humanities/social science classes that I took in undegrad. My favorite was probably 'Religions of the Eastern World,' but I also really enjoyed 'Human Aggression' (an anthro class). Additionally, I took classes in American Government, Literature ('The American Best Seller;' we read Harry Potter, The Wizard of Oz, The Firm, Lonesome Dove, and many others- for a college class! It was awesome), Economics, and Business Ethics. Business Ethics was a fantastic class- the entire class was case-study based. I loved it!
Although I attended large, state universities for both undergrad and graduate school, I'm a big believer in a 'liberal arts education.' I love the hard sciences- always have, always will. All the same, there's a ton of interesting stuff out there in the world that has nothing to do with Biology, Physics, and Chemistry. Humanities and Social Science courses required me to use aspects of my brain that lay dormant in performing calculations, designing experiments, memorizing biochemical pathways, etc. I for one, am really glad that all institutions of higher education require humanities and social sciences as part of a general ed curriculum.
As for advice on how to handle non-science courses, I agree with other posters who recommended office hours. If approached sincerely, TAs (myself having been one for many courses) and profs are very willing to help struggling students- so long as they see you putting forth the effort to improve. Also, I'd advise you to take courses that interest you. Surely, you can't ONLY be interested in science and becoming a veterinarian- what about the rest of the world out there? What lights your fire, makes you think- or even makes you uncomfortable? All of these are great jumping off points. I'd recommend that you not view 'breadth requirements' as requirements- think of them as a chance to get your feet wet in other disciplines- disciplines that will make you well rounded, and able to speak with all sorts of people when you get out into that big wide world. Enjoy them- and have fun!