A few months ago, my brother, Adam, came up with a truly inspired idea. It sent waves of excitement through the New York Mercantile Exchange, where he works; the phone lines hummed with the chatter of his friends; and at every family gathering, we could talk of little else.

The idea? For his 40th birthday, Adam was hosting a Mets Fantasy Camp, where we would play real games, in uniform, coached by retired pros. And it would take place at Shea Stadium.

Everyone invited was thrilled at the prospect of playing in a Major League stadium. Everyone, that is, except me. Like Adam, I’m a lifelong Mets fan; unlike him, I’m a lifelong klutz. This was a situation with a high potential for public embarrassment. But Adam was adamant that I play, and you can’t say no to your brother on his birthday. So clearly some remedial baseball training was in order. First, I did what all nerds do when confronted by a problem: I went to the library. “Baseball for Dummies,” by Joe Morgan, noted author and player, gave me a refresher course on the basics of hitting and fielding. Mr. Morgan was particularly informative about equipment. For instance, I learned that you can break a glove in faster if you put a ball in the pocket and then tie it closed with a shoelace.

A nice tip – except I didn’t own a glove. At Paragon Sporting Goods (867 Broadway, 212-255-8036, www.paragonsports.com), a young sales clerk helped me pick one out with the patience of a trained psychotherapist. I opted for a 12.5-inch Rawlings. The leather had been pre-softened, so it was comfortable, and its $59.99 price tag meant I wouldn’t feel too bad if I used it once and then chucked it in the closet. The clerk also suggested a pair of batting gloves, to protect my tender writer’s hands.

Now it was time to swing a bat. At the Baseball Center of New York (202 W. 74th St., 212-362-0344, www.thebaseballcenternyc.com), my instructor was Mike Eaglin, another patient young man who had spent time in the Atlanta Braves system. Mike tossed me dozens of balls, exhorting me to “trust my eyes” and “turn that back foot out.” It was a little like golf in that power comes from the hips. It was also like golf in that I was terrible at it. But after an hour with Mike, I was definitely swinging better, making contact, and keeping my balance. (Until I saw the $105 price tag for the lesson, and nearly fell over.)

I had similar success at the batting cages at the Field House at Chelsea Piers (Pier 62, 212-336-6500, www.chelseapiers.com, $65 an hour). At first the balls just flew by me and hit the canvas backstop with an embarrassingly audible thump. But after a few more turns I was again making contact, and I began to believe that maybe, just maybe – if the opposing pitcher was weak and I had a good night’s rest and all the planets were in alignment – I could get a hit at Shea Stadium.

The day arrived. It was a cold morning, with those famous crosswinds blowing off Long Island Sound. In the visitors’ locker room, 48 middle-aged men were shuffling into Mets uniforms. In honor of Willie Mays, my cousin Josh had chosen no. 24; for Jackie Robinson, my eldest brother Sam wore no. 42. I had chosen no. 2, for Marv Throneberry, a lovable but lousy first baseman from the Mets’ first season.

Outside, I experienced a kind of awe as I stood on the warning track, the semicircle of packed dirt between the outfield grass and the wall. I looked up at the tiered stands, the scoreboard, the 747 lazily descending toward LaGuardia Airport. For years I had watched the Mets from the stands or on TV; now I was seeing the field from the players’ point of view. It was almost like being in a cathedral, and I felt extraordinarily lucky to be here.

Everyone else seemed to feel the same, grown men smiling like kids as a trainer took us through some stretches. In our custom-made uniforms, we looked pretty good, too. Although the names were a bit incongruous. Haber, Goldbaum, Ben-Levi: Shea Stadium hadn’t seen so many Jews since last year’s Ethnic Day.

Time to play: the Family vs. the Working Stiffs, my brother’s hypercompetitive Wall Street colleagues. Adam put me in left field. Mr. Morgan describes it in his book as “the easiest position to play,” but I was nervous: I realized, as I jogged to my position, that I had neglected to take any fielding practice.

I needn’t have been concerned. Adam was our starting pitcher, and in the first inning he allowed three runs on two walks and two infield hits.

I didn’t get up until the bottom of the third. (I was batting ninth, which, Adam assured me, was “a crucial spot in the order.”) The score was 5-3, Working Stiffs, with two outs and nobody on. The opposing pitcher had a good arm for a commodities trader, but he tended to get rattled if the count went deep. I took the first pitch for a ball; I fouled off the next one. Suddenly I knew that he wasn’t throwing me any strikes. The next three pitches were balls, one of them practically in a different time zone.

“Take your base,” the ump said. I was so excited that I threw off my helmet and sprinted to first.

George Foster retrieved it for me. I repeat: George Foster, who hit 52 home runs in 1977, handed me back my helmet. Then my Israeli cousin, who held the bat almost directly above his own head, hit a weak grounder and was thrown out.

I was up again in the fifth. I was focused as I walked to the plate, but my mother broke my concentration – “Smile at the camera! Would you look at your mother, for once in your life?”- and I heard the umpire call a strike. I barely got a piece of the next pitch, and then I was distracted by my own face in the Diamondvision. Three pitches, three strikes: I had struck out, whiffed, K’d.

We lost, 7-3, so I didn’t get another shot at a hit. Although I had made a decent play in left – charging a hard-hit grounder to hold the runner at second – the walk had been the high point of my game.

I handled my disappointment by following the example of John Stearns, a former Mets catcher, who was at the steam tables, fixing himself an enormous steak sandwich. With a full belly (all that baseball makes a man hungry), I could be more philosophical about my performance. I had done my best, even had some fun, and my brother looked absolutely ecstatic. What more could I want? And besides, I now had a rare opportunity to poke around the Mets’ dugout.

I had always assumed that professional athletes are constantly surrounded by luxury. But the passageway to the locker rooms was dark, with dusty blue tarps for walls, and the dugout’s bathroom was fit for a Soviet prison. The dugout itself was spare, but former third baseman Lenny Randle – who once got down on his knees to blow a ball over the foul line – was effusive. He told me how he used to send the batboys up into the stands to get the phone numbers of cute girls: “You’d say, ‘redhead, fifth row,’ and slip him a 10.” He also showed me where Keith Hernandez used to stash his cigarettes.

And then came two incidents that proved that Fantasy Camp can really provide a small taste of a ballplayer’s life, no matter how unskilled the participant. First, a little girl asked for my autograph. (Granted, she was my niece, but it still felt pretty cool.) And second, when I went to retrieve my notebook from the visitors’ dugout, I saw that some anonymous female had left me a note: “#2 is sexy!”

To learn how to arrange your own Mets Fantasy Camp, call 718-559-3035 or e-mail fantasycamp@nymets.com.