Why we should be passionate/happy in life.

I came up with an idea a few hours ago. I want to run it past you guys - hopefully you'll tear it to shreds in your passion, but this is a good thing. What I'm presenting is not particularly logical, but that's my argument, in a way. It's a chain of thoughts I had:

• We know we're not here for any particular reason, as far as we can tell.
• We also know we're human. We understand enough about the brain to say we are quite meaningful creatures. For example, it is very hard to objectively say 'life is meaningless', because we can almost feel the exact moment when emotion gets involved. What I mean by this, is that nihilism cannot last very long before we either attach a positive or negative emotion to it. That guy who killed himself over nihilism was not happy.
• So we can either say 'life is meaningless, and that sucks', or 'life is meaningless, but that's great!'. We can't cut out the emotion, because we're human.
• Therefore when it comes down to it, we simply have a choice between thinking positively or negatively.
• Most people would, in general, like to be happy. There's no logic to this, it's just an emotion.

I guess what I'm trying to say is, nihilism doesn't work in practice. We're too human to live like that. So, I guess we might as well go with our emotions and live passionately, creating meaning for ourselves and gaining happiness.