Age.

NoOne, can have a real talk about Age without discussing it in these ways
Physical Age
Mental/Cognitive Age
Social Age (think relationships, social vitality)
Purposeful Age (what do you do for 'work' or meaning and how it serves)
Natural Age (How much time are you in nature or the 'wild' & impact environment has on aging)
These things tied together, are where on finds the Spirit - one that's only one's Own, who dares to go near it   :)