I too know exactly how you feel.
I try very hard to enjoy the moment, as at my age, 68, my future is obviously shorter than my past.
I get goose flesh if I stop to consider how fast the last twenty years have gone by. Who knows whether there are twenty to come and how fast they will vanish?
I don't think anyone has satisfactorily explained yet, why everyone finds time moves faster as they get old.
NHS U turn on trans terminology