Every birthday is important, but there are unique customs in Jewish communities for certain birthdays (apart, of course, from the thirteenth birthday of a boy and the twelfth of a girl, when they become a bar or bat mitzva).

Thirty-fifth birthday: It is stated in the Book of Psalms: “You, God, will bring them down to the pit of destruction. Men of bloodshed and deceit will not live out half their days, but I shall trust in You” (Psalms 55:24). Here King David expresses his hope that evil people, “men of bloodshed and deceit,” will not reach half of their allotted lifespan. Since one who lives to the age of seventy is considered to have lived a full life, as the verse states: “The days of our lives in it are seventy years” (Psalms 90:10), one who has reached the age of thirty-five and thereby passed the halfway point to seventy should give thanks to God. Some have the custom of holding a festive meal on this day, known as the lo yehetzu (“will not live out half”) meal, after the aforementioned verse.

Sixtieth birthday: There are certain severe sins that carry a punishment of karet, excision. According to one opinion, someone who is liable to receive karet will not reach the age of sixty. Consequently, one who has passed this age can be sure that he has not been punished with karet. Some hold a celebratory meal of thanksgiving to mark this date, called the “karet meal.” For this meal it is recommended to bring a new fruit or a new garment, so that one can recite the Sheheheyanu blessing on it while having his milestone birthday in mind as well.

Seventieth birthday: Some have the custom of holding a festive meal when they turn seventy, because this age marks the end of the period during which the life of a person who was sentenced to “death at the hands of Heaven” (which is a punishment for certain sins) is supposed to end. Here too, the main feature of the meal is thanksgiving to God.

Further reading: For more on the relationship between couples, see A Concise Guide to Mahshava, pp. 16, 179.