I don't think of the associated depression, loneliness and boredom as being good or bad, they are simply part of a rich mental life.
I am often frustrated by difficulty concentrating, though, and frequently have invasive thoughts as you describe. The things that have helped me most with those are eliminating caffeine, meditating regularly (particularly compassion meditation, peculiarly), and exercise.
But yes, I can relate! I'm very grateful for having a mind that wanders, despite the irritation (it's not unlike caring for a small child I think)