Counting in summers
Weeks are a fine unit for the abstract idea of time, but most people remember their lives in seasons. Summers are the obvious one: holidays, long evenings, trips. A 40-year-old with a 90-year horizon has about 50 summers left, which is a startlingly countable number.
This chart has one circle per summer, ten to a row by decade. Fill a circle at the end of each summer, and maybe write in where you spent it.
Other things it can count
The same 90 circles work for anything that happens once a year: holiday visits with parents, ski seasons, birthdays, Thanksgivings, a yearly trip with friends. Parents sometimes use it for something more sobering: the number of summers left before a child leaves home, which is usually under 18 and often under ten.
Printing
Letter paper works well. The large circles take a marker, a stamp, or a sticker.
Other templates
90 years in weeks
The classic: 90 rows of 52 weeks, 4,680 boxes on one page.
80 years in weeks
4,160 boxes. Close to today's average life span, so slightly larger boxes.
100 years in weeks
A full century: 5,200 boxes for the optimists and the planners.
Life in months
1,080 boxes, two years per row. Big enough to write in.