I agree with T-shaped, but I will add: don't just expand the "breadth" part by learning new languages. Sure, learn a language or two a year, and experience a va

I agree with T-shaped, but I will add: don't just expand the "breadth" part by learning new languages. Sure, learn a language or two a year, and experience a variety of paradigms. But more importantly, broaden yourself with skills that complement what you already have. So if you're doing Rails, get to know Postgres really well. Get to know one JS framework really well. Get to know Chef so you can deploy and manage your apps. Learn C and write a Postgres extension in it. Learn statistics and contribute to a Ruby-based stats gem. Pretty soon you are a "full-stack" developer. And broaden your non-tech skills too: Learn how to write well. Learn some public speaking. Learn how to read financial statements. Learn about marketing. Learn about managing people. Etc.