75 is old in terms of (current) lifespan, which is really what concepts like "dying young" vs "a good innings" refer to.
That functionally you're living a great life is separate from this.
At 75, you are well past the halfway mark of the most optimistic estimates of your lifespan and also, you've already had a long life and have accumulated the wisdom, skills, relationships and habits to reflect that.
Old isn't or shouldn't be a dirty word. It doesn't mean dependant, decrepit, worthless or not to be mourned(!)
If you die over 75, you're not dying young. If children were part of your life, they are grown. You have well exceeded pension age. Whereas if you'd died at 35, you'd have missed out on the last 40 years! It's extraordinarily unlikely that you've got another 40 years ahead, and if you did, they won't be remotely as formative.