The hardest habit for me is definitely habit 2--accept responsibility for your own learning. I'm terrible at self-motivation. I only push myself when there's a specific deadline to meet or people who are counting on me to come through for them. I can fulfill most of my obligations with this approach (even if I squeak in at the last minute!) but it also means I miss out on enrichment opportunities because I don't seek them out on my own.
The easiest habit for me is habit 7--teach/mentor others. People have told me that I'm a good teacher because I'm patient and I explain things clearly. I don't mind going over something step by step with people who are unfamiliar with it--I often get asked to help people on the computers for this reason. Teaching others also helps me solidify what I've learned in my own head through repetition, so that's an added benefit.