I wouldn't say that you have to choose 'PHP' as a career. Its more web programming. Part of the fun, at least the fun for me, is learning new things. First it was CGI, then ASP, then Cold Fusion, next PHP, now I am learning Flex, ruby, and some java where needed. You should have an open mind as to what is out there so you can grab the best tool for a specific task.
Any programming job you are going to have the 'boss' breathing down your neck. If you are on your own then its the customer breathing down your neck. Personally I find deadlines with consequences keep me from goofing off. Other than the deadlines all the programming jobs I have had have been pretty much the boss saying, "I have no idea what you actually do, all I care is that it does X and is done by Y". So if you get a boss like that you have the freedom to get the job done however you see fit in whatever language you feel is best. If someone was telling me how to code though I wouldn't like it.