More or less
You can either seek to get more out of an opportunity (job, technology, interaction, person, moment), or less.
More exposure, more risk, more upside, more work, more learning, more engagement, more passion, more chance to be blamed, more opportunity to make a difference, more effort…
What you’re doing right now is all that matters. Let the rest go, and enjoy the fish you’ve already caught.
I don’t think these are mutually exclusive. Zenhabits seems like they’re talking about breadth, and Seth talks about depth. Focus on a few, important things, and go deep.