J.J. Sylvester, who coined the term Matrix, pointed out that Leibniz, Newton, Euler, Lagrange, Laplace, Gauss, Plato, Archimedes, and Pythagoras all were productive until their 70s or 80s.
“The mathematician lives long and lives young,” he wrote.
“The wings of the soul do not early drop off, nor do its pores become clogged with the earthly particles blown from the dusty highways of vulgar life.”
Sylvester himself was his 82nd year, in 1896, when he “found a new enthusiasm and blazed up again over the theory of compound partitions and Goldbach’s conjecture.”
Another mathematician Harold S. M. Coxeter (9/2/1907 – 31/3/2003) attributed his longevity to love of mathematics.