Code up to professional quality in your free time. Learn new tools frequently, and apply lessons from new languages into old languages. Write your own compile

Code up to professional quality in your free time. Learn new tools frequently, and apply lessons from new languages into old languages. Write your own compilers and interpreters, in order to understand the requirements, expectations, difficulties, and habits of compiler and interpreter implementations. Design your own languages, in order to understand the requirements, expectations, difficulties, and habits of usable language design. Give yourself at least ten years to become a half-decent programmer. Anyone who considers themselves half-decent who hasn't been doing it for a decade is probably kidding themselves; anyone who is considered by their peers to be half-decent who hasn't been doing it for at least a decade is probably surrounding themselves with incompetent peers. Listen to your coworker. Get his specific complaints, determine what general rules you can gather that would assuage his concerns, and ask him if those general rules are the correct ones. If he can't give you specific complaints and general rules, he's talking out of his ass and playing status games; if he can, then no matter his manner of speaking, his criticism is constructive and valid. After all, bad code is a big problem, and at best puts extra work onto your coworkers. If you cannot ask your coworker what he means by his criticisms, then you're probably sunk, unless some other coworker can explain it. But, as a junior dev, your code probably is bad -- the state of the industry is bad, and most code is awful, including that written by people who are ostensibly senior -- and you will benefit immensely from learning to write better code.