Ask HN: How do I keep my skills up to date?

Even though I have over 5 years of experience in my field, I gained probably 80% of my knowledge during a brutal stretch at a startup where I worked like a dog.

I'm very proud of what I accomplished there, but I don't think I want to be in that type of environment 24/7.

Now I'm back at a regular Big Co. Inc. where there is a specialized role for everything and I have a great fear that being in this environment will make my skills be obsolete eventually.

My question is, how do I keep my skills up to date? I've always relied on external motivators (grades, work projects, work deadlines, etc.) so I don't know if I can keep up with just my own projects. Even then, the diversity of problems I solved before would have been hard to think of on my own.

My current thought is to try to get more hands on at work, but this will become harder and harder over time.

What do I do?