Keep them in your memory. Both your parents, and your kids. The only other things we have in life are friends and time.
Happy birthday, and many many more.
Sometimes I wonder how many kids I have in memory because now my two kids are mostly grown. But I remember them each when they were babies, and when they were toddlers, and so on. There's probably six or seven different identities for each kid that is quite distinct as each has grown. The cool things my 17 year old son does and says now are not the same kinds of cool and memorable things from when he was little, but they are just as precious. The rich library of memories I have about them is very impressive to me.
There's a lesson in your reaction to today. Your parents were good enough to be remembered fondly by you. It wasn't easy for them to be good enough to rate that admiration, so remember how they succeeded at that, and try to do the same for your kids. A lot of parents fail in that one basic thing.