Maybe I should have added a corollary.
I'm assuming you already have a solid business model, or at least a well-defined market. "Adsense" is not a business model.
Also, monetization is NOT hard if you're selling something people want.
Getting traffic is hard. Monetizing is trivial if you're running an actual business and not a hobby.
And what, pray tell, is the difference between a business and a hobby? I became an entrepreneur precisely because that allows me to focus on doing what I like doing and doing those things in a way that I can feel good about myself. To me, that means my business /is/ a hobby, even though I'm full time on it now.
Also, monetization is NOT hard if you're selling something people want. Getting traffic is hard. Monetizing is trivial if you're running an actual business and not a hobby.