My grandfather was a very smart guy. In fact, he FIRE'd even before it became cool... he retired in his mid 40's by just saving, investing, and living a very modest lifestyle. He was actually my inspiration for wanting to do the same.
He had a lot of good advice that he dished out, but the piece that stuck the most is something you've heard in one form or another... when everyone's running in one direction, you run in the other.
That works for the stock market, real estate, and even just everyday life.