I’m 72 years old. If I practice 1.5 hrs/day, which is a bit aspirational but within the realm of possibility, I’ll be about 90 when I finally get to 10,000 hours!
On a more serious note, I think it’s really all about the quality of practice, focusing on specific skills that I want to improve, developing musicianship, and having fun! As Stu Fuchs, another great teacher, says – “drop by drop, the bucket is filled.”