I’ve been waking up early for the past ten years. This habit has carried over, and has served me well, now that I have children. I sleep early and wake up a few hours before everyone else in my household. I use this time to work on what I deem to be the hard stuff.
Everyone struggles with controlling attention, so try not to get distracted on the first hour of waking up.
It helps to have something difficult lined up, such as going to the gym (or going for a walk indoors when its raining). Also, it helps to have something easy enough lined up, such as a failing test from yesterday’s work session.
Certain tasks, such as planning and reflection, require some headspace to be effective. I do these things early in the morning, too.