Also over-thinking can cause depression, we are over analyzing things that doesn't happen, and we became the enemy of ourselves and self sabotaging our present moment instead enjoying now, we dwell inside our brain and wasting time on stuff that actually we don't care.

"We suffer more often in imagination than in reality"- Seneca

it was hard for me to avoid thinking our past and future, what i did first was doing something that keep me busy, until we forgot things, sometimes it occurs frequently, that we cannot avoid, all i did is just let it flow and move forward and enjoy the present moment. :)