Finding an appropriate mindset

Hello,
I'm currently entering my second run at online poker. A while back I started playing and quickly started building a bankroll. I then thought to myself "Wow, i can make money doing this." and proceeded to do all the wrong things. Played when I was tired, didn't concentrate, played limits I still didn't have a bankroll for, tilted, started playing bad and lost everything I gained.

This time, I've seen the same start as last time. Jumped in, am concentrating well, playing at limits I can afford and have again multiplied my initial investment 5 fold. I don't want to make the same mistakes!

What is the appropriate mindset though? I am a firm believer that one should set goals. I'd like to set a small goal, say "Make enough to pay my utilities". I do, however, especially understand the importance of building a bankroll. Is it better to set a goal and make the withdraw's, or just (hopefully) let my bankroll grow.

I make no misconceptions about 'going pro' or having a sizable second income at this point. I'd have to get ALOT better before that's a consideration. I just don't want to make the mistakes of not taking my bankroll seriously or not keeping a pulse on my progress.