Past regrets and future worries are the main ingredients in a soup called suffering. Masters recommend seeing through the dream like quality of these in many words such as time is in the mind, only the now is real all else imaginary thoughts and that history is just a story.
The difficulty in truly accepting and understanding these arguments lies in the fact that the present or now seems so real. And that past events were at one time felt just as real as the present does now. So how can we possibly say that the presence is real but not the past? Or that the future will not be similar to the real now.
The answer lies not looking at just the past or future as dream states but deconstructing the present as being unreal. This is impossible as long as we use our senses which report a very real direct experience of the now.
But there are two components of this now. There is the sensory experience including the sensation of thought. And overlaid on them is a fog like story that keeps swimming in our brains. We are dreaming even now. Separating these two into a directly observable experience now and a thought based conceptual commentary often labeled, I, me and self. And seeing that this manufactured self is not real and never to be found.
The absence of self now must mean an absence of self in the past or in the future. This diffuses suffering substantially.