The 60th birthday is a big one to Jews, for it means one has avoided at least one of the definitions of karet, which is premature death. And with it one is officially welcomed into the ranks of zikna, old age (Avot 5:25), however unworthy one may feel of admission just yet.At 50, I joked that I was now too old to die young. Now, I’m even too old for a mid-life crisis. I can’t say I feel old, but I’m acutely aware that no one looks at me anymore in terms of potential. If one’s company goes bust or law firm closes, new employers will not rush to hire someone of 60, certainly not at previous levels of remuneration. But at least for now, I’m more worried about finding the time to complete current projects than not having any more projects.Other than finding it hard to believe that a decade has passed since I wrote “On turning 50” – the passage of time seems to accelerate sharply with advancing years – my chief feeling on reaching this latest milestone is gratitude. One of the greatest political put-downs I ever heard was former Texas governor Ann Richards speaking to fellow Texan president George H.W. Bush: “He was born on third base, and thinks he hit a triple.” I can’t say whether that was fair with respect to Bush, but I spend a lot of time making sure it is not true of me.I know I was born on third base: My parents loved one another and their five sons; we knew no material want; and each inherited enough talent that the world was ours. Home politics were vaguely liberal; the values decidedly conservative. It would be hard to find another family of five, in an upper-middle-class Jewish suburb and attending elite universities in the ’70s, who had no interest in drugs or liquor. My parents told us that being Jewish was the most important thing about us, and thus had only themselves to blame when four of us took them seriously and came to Israel to find out more about Judaism and ended up staying.Above all, I’m grateful that I have no desire to go back in time. I wouldn’t claim that I’ve never been happier – who can remember or compare? just that I would not wish to be any other age. Looking at pictures of myself with black hair, even without the college Afro, I think “Too much.” When I watch my children chasing after their young ones, or listen to them complain of sleepless nights, I wonder how I had the energy for that. If I wonder aloud, they are likely to answer: “You didn’t, Abba. Ima did.” In any event, I have no desire to switch places with them.By 50, I had already made peace with the fact that I would not be the first Jewish president. And contemplating the course of America over the past decade, I can add “Thank God.” It seems to me that those who set out to change the world for the better are more likely to make things worse – often much worse. The ambition remains. But the traditional Jewish approach makes much more sense: Bring divine blessing to the world through every thought, word and deed. God will certainly know how to apportion His blessing in the most efficacious possible manner.I expressed the hope at 50 that my wife and I would merit to marry off over half our children over the coming decade, and that by the end of the decade grandchildren would be coming in bunches. Those prayers have been answered.The beginning of zikna, at least, strikes me as much like the Maharal’s description of the special simha (joy) of Succot – the holiday of gathering – where after all the labor of the year one can contemplate the fruits of those labors, and express gratitude to God, without whom those labors would have been for naught.With respect to the achievements of our children, I try to follow the example of the father of a young rosh yeshiva in my neighborhood. Once I said to him, “You must be so proud of your son.” To which he replied, “Not proud. Grateful.”My inability to see much of myself in my children, especially the more disciplined among them – helps guard against pride, and increases the gratitude. What does give special joy is the realization that my wife and I have produced a family out of many diverse parts. And each new son- or daughter-in- law becomes a part of that unity. One sees it in the way the brothers dance together at each other’s weddings, and the efforts my daughter and her sisters-in-law put into making sheva brachot for the new couple. But most of all in the way everyone seems content on family vacations to do little more than sit around talking to one another and watching the kids play.Life has not yet become only a matter of savoring the fruits of long ago; there is still lots of room for discovery. Rarely do I travel abroad without making a new close friend. Scarcely a month passes without the discovery of some stimulating new thinker – most recently the magnificent essayist Walter Russell Mead – or a set of Torah shiurim that uplift. I still have plenty of ideas I want to share, even if recall of the words needed is sometimes delayed.One relief of advancing years is that the physical side becomes less in control. I cannot even fantasize about a possession I think would make me happier – with the possible exception of apartments for the kids. That doesn’t mean that the yetzer ra has run out of tricks. I’ve interviewed enough people whose greatest achievements were behind them to know that the need for honor, unlike physical desire, often increases with age. During a heated rabbinical discussion, one of the older rabbis present began: “I’m over 80, and so cannot be suspected of being concerned with my honor...” At which point an equally senior colleague interjected: “The suspicion has never been greater.”At 50, I could boast of being able to run further and lift more than at 40. I won’t be able to make the same boast at 60. My orthopedist tells me it will take surgery and six weeks on crutches if I ever want to run again without pain.But even the intimations of mortality found in physical decline are not without benefits. They remind me that projects like finishing the Talmud can no longer be put off to the future because the future is not unlimited. Now is the time.Best of all has been sharing most of the journey, and hopefully decades to come, with my best friend – the one person with whom there can never be too much time alone.The writer is director of Jewish Media Resources, has written a regular column in The Jerusalem Post Magazine since 1997, and is the author of eight biographies of modern Jewish leaders.