An expression that I eschew with extreme prejudice is: "I will never forget <some seemingly important event>" The reason I recoil from this expression is, of course: I haven't the slightest idea what I may or may not forget. Goodness! I have forgotten so many things that at the time seemed so unforgettable. That being said, when the "something" causes a change in how one conducts his life, then that "something" certainly can be said to be unforgettable. Even if one were to lose the ability to recall the details -- or even the occurrence -- of the original event; the change is engendered in one's journey through this world and trajectory through the next. Nonetheless, such an event is intrinsically unforgettable. I herein relay two (which will become three) such experiences where the rosh yeshiva, R' Chaim Dov Keller, זכר צדיק לברכה, changed the trajectory of my life. Every event in life is actually a mussar lesson. For a couple of years...
This is a paraphrase of the pasuk in t'hillim 84:7 -- "mei'chayil el chayil" -- which means "from strength to strength". In this case, it is my thoughts and ideas to those who are strong enough to be interested :)