Miss x. My mum is almost 60 and I know it sounds old and decrepit but trust me she is the best Nanna. My DS loves her to pieces.
They go swimming together. To the arcade. Bike riding. Kite flying. To the movies. Crafty stuff. Play xbox. You name it!!
60 isn't old! In fact even my 85yr old grandmother is still really active and healthy. So don't let it get you down! DHs mum is 62 and did a round the world backpacking trip!
Still plenty of bite left in your 60s+70s!!