During my first year of working, I was offered to work part-time at another company. I actually took it to my supervisor and asked for his advice.

He began with a sigh, he knows that I like programming so much and wants the job because I wanna do more programmings. He gathered his thoughts and said calmly, "Look, I cannot stop you if you want to, but think about this, you already are doing programming for five days a week here. Take those extra times you have to develop other parts of yourself. Go learn public speaking or something" or something along that line.

I gave it a deep thought, took the advice, and rejected the offer. I eventually went on to commit myself on volunteering for the next two and a half years, and secured a promotion about a year from that conversation because my supervisor sees improvements in my communications with others and my soft skills in general (unlike programming, you can't volunteer in an organisation without speaking to people).

Sometimes we programmers only wanna code that we forget that what we're building are for humans and involves other humans. You wanna be the best at work? Try to grow on your horizontal axis, too.