There are usually desperate, miserable and unhappy portraits of old people, but this is not one of them, this is my "super grandma"'s version..
She has been in bunch of extremely hard sittuations in her whole life (as you can see from her wrinkles) but she always know how to kept herself strong, cheerful and unic.. The energy comes from: her own way to be happy; it's about to search/find little details - loveable sides of this odd life and feeling the purity of the nature..
You are entirely right. It is rare to see an older person radiating such a spark and zest for life. Congratulations, may you have great times together. Best I