A few days ago I had a similar insight - that all that really exists is only the present moment. And that was the only guarantee ever. I had read about this multiple times before, but this was the first time I felt it in a very real, alive and visceral way.
This insight also showed me that thinking about the past can resulting in 'analysis in hindsight' and thinking about the future in trying to project the past to the future. Both of which make me lose trust in life and God and feel insecure. So the only way is to decide to be happy right now.
These seem rather simple, but somehow since having this insight, life has changed. Not completely, but bit by bit. Somehow the bonds to the past seem slightly looser. One way I think of this when I forget is the analogy of a line on a blackboard. My life is currently a dot on that line, and I consciously erase the length of line before that. This helps.