the concept of time is simply there for people to recall things or anticipate something for the future. when you realize this and realize how the silly the concept is you'd stop giving a damn. the past can be 3 seconds ago or 30 years ago, the point is your fixation it on a time and that's where (or when) it is.
your unwanted thoughts become a thing of this past after they leave your awareness (and you stop thinking about it) so there's no point in worrying about them if they become a thing in the past and that past ceases to exist because the past= time and these concepts don't matter
what does matter is your present moment. your "now" can't be recalled nor can it be anticipated. it's just now. that's all there is. what you are now is something that can't be denied. YOU cannot be denied. with your perceived past or future you the common denominator has been you as the main character. you never stopped existing. you might have changed states from "sleeping" or "dreaming" or "imagining" but it's always been you and that cannot be denied.
do what you want with this information