In today's Gospel reading at Mass from John 16, Jesus knew that he's going to the Father in a little while and he told his disciples that they would weep and mourn, but their grief would turn into joy. When that happens, they would no longer remember the grief.
I can recall my own past sufferings and pains, both physical and mental; but since I am enjoying the Lord so much now, I don't ever think about those days anymore (no regret either). "When you are in love, the whole world looks beautiful" ~ it has that kind of effect. With Jesus, joy always wins out. Looking ahead, we see eternal life awaiting us in heaven and all present sorrows will be forgotten ~ so why not start "forgetting" them right now?