To prevent over-thinking at the time of sleep you can try a simple meditation technique I had shared a while ago which I've been following for several years https://news.ycombinator.com/item?id=17906598

Regarding how to be in the present reality: It is a natural tendency of conditioned mind to worry about the future and be guilty about the past. Ordinarily such a mind can only be in present moment when it's involved in doing something it likes. However, you can train your mind and learn the skill of being in present moment by following a simple technique. Ask yourself this question frequently throughout the day "What am I doing right now?" whenever you raise a question your mind is by its nature compelled to give you answer. SO asking this question will break whatever train of thoughts your mind has been riding through and bring you to the current moment. Now ask another question, what should I be doing at this moment? and then focus on the thing you should be doing (as in focus on eating food or sipping coffee). This technique is taken from mind full to mindful (https://amzn.to/2phvft7 )

Above all, in my personal opinion, it is important to realize that most of things that happen to us can't be controlled/managed by us. The universe is infinitely huge and I'm just a tiny spec of particle compared to its magnanimous size. A change in prospective is required which makes us focus on the deed (karma) we are supposed to do and stop focussing on the result/fruits (phal) thereof. Meditation/chanting can help in realizing this reality.

Try Cold showers . Working well for me. Also read - https://www.amazon.com/Mind-Full-Mindful-Wisdom-Monks/dp/935... (Thank me later.)