Advice for vows

I dearly love my fiancé and have started with writing my vows. I’ve added many personal, heart felt things and a couple of promises to him.

I don’t have trouble with finding things to write, I can rant on for days but I want to add some things in there that could be of help in the future after many years.
Has anyone experience something like that where years later they feel they should’ve added this thing in their vows? Something they learn later on that’s valuable and important.