In this season of life (I’m 74), freeing myself from nostalgia is one of the biggest battles I face. It is a daily struggle — mental, emotional and spiritual.

My wistful affection is not for the past as originally lived but as I reconstruct it now, often in rosier hues.

My nostalgia doesn’t take Sundays off. My wishful Mennonite mind can easily conjure a not-so-distant past of church pews filled, institutions thriving, marriages never ending in divorce.

Now, there is nothing wrong with an occasional mental excursion into the past. Why would I teach history — an investigation into how the past has shaped the present — if it were not an instructive and enjoyable exercise?

But nostalgia involves more than an outing to the past. It is an attempt to return and reside there, in what, I so quickly assume, had to be a simpler, better time than the messy present and uncertain future.

How comforting, but how illusory.

When one gets older and one’s body begins to break down, it is tempting to think the world is falling apart along with you.

Most of my life is in the past, so why not be content to live there?

A recent Broadway production of Thornton Wilder’s Our Town brought home the pointed admonition: If given the chance, from beyond the grave (or later in life?), do not go back to a time and place lovely in your memory. The second time around, you will want to cut the visit short and repent of the wish to return at all.

If a playwright’s cautionary tale will not suffice, then look at what is happening on the national stage with the impulsive actions of a 79-year-old leader whose slogan and agenda (“Make America Great Again”) is nostalgia writ large.

His formula for renewed greatness lies in a mishmash of the 1980s (growing budget deficits, weakened social safety nets), the 1950s (pre-civil rights and women’s movements, White males calling the shots), the 1940s (internment camps), the 1930s (high tariffs and trade wars), the 1920s (restrictive immigration) and the 1890s (no income tax and a tiny federal government).

These old times and policies, with some new ingredients mixed in (the ICE deportation machine) may be lovely in his unique memory, but ­hardly in many others’.

“Honest politics cannot revolve around ‘again.’ We can only go forward,” the politician Pete Buttigieg said several years ago. I would extend this observation from the political to the personal. Collectively and individually, we must look forward rather than gaze backward at a past that deserves, in many ways, to be left behind.

How, then, to fight the pull of nostalgia?

A first step is to acknowledge that the past is a mixture of shadow and light, sorrow and happiness, the best and worst of times. There is much to cherish but also to regret and to not want to live through again. A careful study of the past — history, in other words — will dispel the idea that life was better then.

A 1974 book title drives home the point: The Good Old Days — They Were Terrible! In it, Otto Bettmann shows how, from health and food quality to working and living conditions, life in late 19th-century America was good only for the privileged few: “For the farmer, the laborer, the average breadwinner, life was an unremitting hardship.”

I have been fortunate to have children and grandchildren. Focusing on the choices and opportunities they face — and how I can be of help — will stop me from spending too much time teary-eyed over the pictures from their “cute” periods in photo albums.

Finally, the Bible is free of nostalgia for a pre-Fall paradise. There’s no suggestion that a return is possible or desirable. Nor does one find the idea of a period of innocence in one’s life that should somehow be recovered.

Instead, the emphasis is on awaiting and perceiving God’s new activity in the present and future. “I am about to do a new thing; now it springs forth, do you not perceive it? I will make a way in the wilderness and rivers in the desert” (Isaiah 43:19) is but one of many scripture passages that can help free me from the lure of nostalgia.

J Robert Charles of Brooklyn, N.Y., is a member of Manhattan Mennonite Fellowship. He teaches history and politics at St. Francis College in Brooklyn.