[knave]

I'm trying to start a business, with a friend of mine. We had to do some catching up on the knowledge in the field (a specific computer science field). In the past six months, we've read a graduate level text book and dozens of papers published in the ACM and elsewhere.

I felt exactly the same way you did until recently. I'm 27 and I've been in the software industry long enough to feel like I'm starting to get dumb. I've forgotten how to do integrals, compute eigenvectors, all that good stuff we learned. But doing all this research has gotten me fired up again. We had to (re)learn graph theory, set theory, relations, lambda calculus, and some more specific techniques that build on those.

So my advice to you? You can do it on your own, you just need sufficient motivation. For us, it's the business (the fun of it, and the prospect of it making us rich). For you, it's whatever gets you fired up.

By the way, the internet is an incredible resource. It's a double-edged sword, of course. I tend to waste a lot of time just reading blogs and playing stupid flash games. But when you need information, it's almost always out there. Scientific journals, university web sites that publish course notes (in particular, MIT's OpenCourseWare is incredible), and Wikipedia & friends. Decide how you want to improve yourself, and the resources to do it are at your fingertips.