I found that a two week long vipassana meditation retreat was a great way to really come to appreciate being alone with your thoughts. I experienced a clarity of mind I pretty much never experienced in my life up to that point, mostly from spending two weeks of having no choice but to be alone with myself. It’s materially different than a 20 minute interlude of solitude/meditation (and also far more difficult both to make the time and to persist through it), but also very rewarding.