The Rebbe's guidance on long life — asking for it, and what brings it:
Asking for long life. Seeking blessings for a long and good life is itself a Torah commandment, and the Rebbe gladly prayed on the petitioner's behalf (IK 3622). He blessed people for health, long life and nachas, together with daily spiritual nourishment — Mishnayos by heart and the daily shiurim of Chumash, Tehillim and Tanya (IK 5446).
Mitzvos that bring length of days. Tefillin put on every day (except Shabbos and Yom Tov), even if not in the morning, bring long life (IK 1323). The mitzvah of tzitzis is fulfilled continuously for as long as one wears them (IK 2619). Charity given in one's lifetime rather than postponed brings added blessing (IK 5147), and supporting Torah institutions carries a blessing of long life (IK 8720).
A will. Writing a will, prepared by a lawyer, is itself a segulah for long life (IK 1091, 3652).
Milestone birthdays. On reaching sixty, seventy and beyond — the meaning of each age in Torah sources, and continuing one's work with renewed strength — see IK 2360, 8749, 7469.
See also: Personal growth – Birthdays and how to mark them; Mitzvos in daily life – Tefillin, Rabbeinu Tam and tzitzis; Tzedakah – A source of blessing for health, livelihood and family; Health – Old age and elderly parents.