I've re-established the habit of recording the time I spend practicing. I record the times to the minute, rather than close estimates - if I sit down at the piano at 4:52, I'll write down 4:52 not "ten to five".

Even though there's no one checking my diary for practice times, it helps keep me focused and I'm more likely to practice for the length of time I've committed to and to meet my goals within the practice session.