I am not motivated to brush my teeth, finding almost any excuse reason enough to procrastinate. One common excuse was that the brush was not sanitary.  Here's how I have solved that, with an old thermos bottle.

After using the brush, I rinse it first with clean water from the tap, then with boiling water that goes into the thermos, followed by a final rinse with hydrogen peroxide solution, which also goes into the thermos.  Finally, the brush goes into the thermos, where it stays capped, away from air and contaminants.

I use the previous contents of the thermos as mouthwash, so I always have a clean mouth and a clean toothbrush handy.

P.S. I keep the thermos in the kitchen, where I spend a lot of time before and after meals, and where boiling water is easily produced.