Waste no tears over the griefs of yesterday?

Yes, I think that's a perfect way to put it. The past is the past, and lingering in the greifs of yesterday will only bring a heartache that wont subside. You don't ever have to forget, no don't ever forget. But wasting tears on the past will keep you from bettering the present. There's a time to greive, and a time to move on. You cant do both at once so make the choice.