In order to be happy, we need to set the intention to start anew everyday. The past has two components: what happened (the fact) and our emotions associated with it. Acknowledge what happened in the past, but don’t carry with you the emotions.
We don’t deny the past, but the truth of the matter is that the exact thing that happened two months ago is no longer happening at the moment. However, what still remains is our feelings.
Without paying attention, we keep the emotional reaction to a past event within us. Overtime, we accumulate so many feelings lingering from weeks and months ago that we become a creature completely controlled by our past.
When we let these emotions stay within us, they turn into a memory of a kind. Because they are repeated for an enough number of times, they become our behavioral pattern. So next time, when somebody does a similar thing or says similar things to us, that emotional reaction comes up again, as the mind has been trained to react that way. And we pile up agony, anger, envy, or disappointment.
In order to enjoy life, we need to let go of this emotional reaction right at the moment we see it happen. Let it slide into the past as if it no longer exists. Only then, we are able to start everyday, every moment anew and live in the present moment, completely shedding the burden of the past.