illustration (attribution, if any possible, is at the end of the article)
If you don't live now, you will not live when the future comes. For when the future will arrive, it will be the new 'now', and you'll be thinking of a further future! So pay attention now, to whatever you do (with your body, and with your mind).
This doesn't mean that only the present exists… You presently make the past exist (by picking what's worth remembering or using as 'explanation', and what's discarded as irrelevant events—the past is an individual preference, usually quite obvious in how each side of a war sees oneself). You also presently make the future exist (by picking what's worth planning for or worrying about, and what's discarded as irrelevant possibilities).
What this means is that there's one point in time when you can actually affect the world, when you can forgive and let go of the past, when you can shape the future… and this is the present (neither fully determined by, nor fully independent from, the other times).
As long as you "should have done this-or-that", as long as you "will 'soon' do this-or-that", you're locked in the samsaric perpetuation of a mere narrative, a story about yourself, and a prison for the ordinary mind: such a story requires not to change the past and to keep the future as always in the future, just so that the story is stable and reassuring, just so that the story gives you a (delusional) sense that you 'know' who you are…
You can waste your present talking of forgiving, in the future, events from the past (i.e. you can make your present about making sure you perpetuate a source of suffering that is worth the mention)… or you can constructively forgive now, by letting go (now) of the narrative about who you are, by realising selflessness!
You cannot be free as long as you tie yourself down, never wanting to walk too far away from 'your' past, 'your' story, what 'you' went through, 'your' path, 'your' life!
This doesn't mean 'the' past doesn't exist; it means other narratives over the same events (e.g. a narrative of overcoming challenges) can be appropriated… and you're the one picking and appropriating! You can see 'your' past as a "defining moment", or as a "historical blip" in the grand scheme of things! And if it's a blip, does this story really need all the attention you're giving it?
Forgiving is forgetting the 'personal' take on the events. You never truly forgive as long as you make sure you don't forget, as long as you ensure it stays relevant to 'you' long after the situation has changed. A blip is not worth remembering… The classic interpretation of "forgive but don't forget" is about "lessons learnt", but said lessons are implicitly assumed to be contextless and permanent, which is delusional! Moreover, at best, any lesson is about causality, not about whether it happened to you specifically or to someone else!
Forgive, forget who (you think) you are; look, discover, expand, grow! "Forgive but don't forget" is just making sure you keep with you, at all times, something painful and stressful… just so you can reassure yourself you know who you are. But you don't know who you are, memories change (the more often you access them, the more they do) so you don't need to carry the pain around like a reliable crutch for your ego, it isn't reliable. And while this lack of reliability isn't 'satisfactory', clinging and grasping will not help the situation.
If you don't live now, you will not live when the future comes.
If you take things personally, if you don't forget, then you don't live now, you're only writing down a 'defining' / 'reifying' story of someone you identify with, you voluntarily put yourself in chains! Of course, "not taking things personally" doesn't mean there's no response to give at all; the situation may very well call for a response free from individual preferences, prejudices, biases, tendencies or self-centredness, a wise response! Don't plan to 'forget' the self once you'll be enlightened; forgetting the self is how you'll awaken (seeing reality as it is, without making it all about "me, myself and mine")!
photo: "breaking bonds" by DarkSky0094 (darksky0094.deviantart.com/art/breaking-bonds-210354696)