Get into blogging because you want to write. Get into blogging because you want to document a stage of your life. Get into blogging to be able to comment on things in the public sphere. But don't get into it for the money. Throwing some Google Adsense ads on your site is fine, but if you think you'll receive more than pennies a month you're setting yourself up for failure.
I started this blog because I became deeply interested in personal finance and figured this was a way to track my financial growth and development. It will also give my future self a snapshot into my mind at this very moment. It remains to be seen how long I'll last.