You can't function well without adequate sleep! I think the most
important advice I can give anyone is to know yourself first --
your strengths and weaknesses, and then capitalise on your
strengths by focusing on endeavours you're good at. And that's
different for everyone. There's no one-size-fits-all path to
success.
But hard work does matter. Bill Gates didn't get to where he is
today without it, even tho he's probably of high innate
intelligence in the first place and would have done well without
formal eduation. Not everyone is of that calibre, by birth.