The mind attached to thinking is a prison. I know, I've been there all morning.
The only way I know to get out of this prison is mindfulness. To be fully present with what you are doing right now requires not ruminating. You can't both have a thought, and be fully in the present with the five-sense-world around you, at the same time. (You can however have mindful awareness of thoughts arising and fading away, which is good also).
I'm off to sit and breathe for a while. It is the only way out of prison I know of. Stuck in thoughts of past and future creates GREAT suffering for me. Time for some 'time out' - literally letting go of time by not holding it in my awareness, allowing the breath alone to fill my awareness.
Some people get more sukha than I in this life, some get more dukkha than I. But the lot of us have the same problem - we identify with our states of mind, whether sweet or bitter, and our identification is bondage.
These are the humble thoughts of a worldling who, through just a few glimpses of the sublime Dhamma, has just enough conviction to keep going.
Then the Blessed One, picking up a tiny bit of dust with the tip of his fingernail, said to the monk, "There isn't even this much form...feeling...
perception...fabrications...consciousness that is constant, lasting, eternal, not subject to change, that will stay just as it is as long as eternity."