"You never have the energy to do anything," my son said scornfully Friday night.

We were at a playground, an unplanned stop on our way home from the grocery store. I was hungry, and frustrated from another fruitless day of attempted sales. I reacted with unnecessary anger.

"You wait until you're my age!" I said, then, realizing how ancient I sounded, I backpedaled. "Or even ... 30!

"Playgrounds won't be so interesting to you then. That's why they're designed for kids."

Sometimes, I enjoyed the playground. Who doesn't love an occasional swing? A trip or two down the slide? Sure. And the monkey bars? A test of my upper body strength. Occasionally, we'd play a game of tag, charging up and down ladders and slides, scaring the other parents who gaped up at us from their benches below, and exciting the other children. My time limit for these activities was always limited. Robby was inevitably not ready to stop. But never had he expressed it this way.

I was pretty sure I was more active than most parents. Lately, however, life in general had made me feel old. And so, his comment stung. But my response made me feel ancient, as though my best days were behind me.

Saturday, we returned to the same park for what will be a weekly kickball game for single parents and their kids. The 11 of us divided into teams and played an amusing game of kickball. Amusing because all of us adults attempted and utterly failed to catch perfect pop kicks. Amusing because some the kids seemed particularly disappointed in us, even embarrassed, for this. Amusing because even though Dave kicked missiles, he was nearly hyperventilating with exhaustion. And Dennis didn't run for the ball; he jogged lightly, his feet barely leaving the ground, sweat beading his forehead.

I no longer felt alone. In fact, I felt fantastic. Because clearly, of the five of us, I was the most energetic. I was a little ashamed of myself, glorying in the good health I was lucky to have. Yet, remembering my son's disappoint expression of the night before, I felt a small sense of redemption.

After the game, we drove to a barbecue hosted by a member of the same group. The kids fanned out into a common area in the middle of the townhouses there. Out came soccer balls, croquet balls, Superballs and footballs. My son was in kid heaven.

Me, I hung with the adults, sitting on the grass, conversing about things like how fast our kids were growing, what they would and would not eat, how tough it was to be a single parent, how much we all looked forward to getting out with other adults. Eventually, I grew weary of the conversation and found my son. We batted the soccer ball around for nearly half an hour until someone shouted, "Let's play a game!"

It was normally at this point that I would disappaer into the house, or find a comfy lawn chair from which to safely watch. Uncoordinated as a child, the last one picked for almost every grade school game, I am not about team sports.

But I was already standing in the common area, among the dozen kids and three other adults who were gathering to play. I glanced longingly at the cluster of adults on the deck. They chatted and laughed, and watched curiously as we formed teams. There lay my comfort zone. But no matter what I did at this point, I would obviously be slinking away.

My son was already setting up the goals. I knew he wanted me to play. I could not disappoint him or myself.

We divided up into teams: Six small children, three teenagers and only four adults.

The game began.

I flinched the first time the ball descended upon me from above, and from there on, my teammates knew to take over from me in those situations. But otherwise, I needed no help at all. Caught quickly up in the competition, I found myself in the middle of the fray, kicking without hesitation at the ball, prizing it away from the well-practiced, teenaged members of the opposing team, steering it clear of my son, the opponents' goalie.

It was not a gentle game. Two children were knocked out in a row, one when the soccer ball hit in square in the gut and stole his breath, another when the ball slapped him in the face.

The teenagers were not going easy on any of us. I took kicks to the shins, a soccer ball cheek smash as well as a ball to the crotch.

I was far from good, obviously unskilled in the game. But I was also far from the sidelines. Breathing hard along with not only the other adults, but the younger players as well. The sun had gone down. The night was chilly. My shirt was soaked with sweat.

"You've gotten so aggressive in the last half hour," one of my teammates said during a break in the game. "I love it!"

I scarcely acknowledged him. The ball was back in play. Robby's team won by one point. Both teams came together in the end for a group High 5, something I had never before done.

My limbs began to complain about it all shortly after we got home. I popped two ibuprofen pills, then fell into bed.

I dreamt that my legs had ceased to work and throbbed with pain. I was attempting to cross a city street, but instead of walking, I was dragging myself with my hands, my damaged legs trailing behind me. It was the dark of night. Light, cold rain fell. I looked up, and saw headlights closing in on me.

I woke up. My legs were functional but oh, how they throbbed.

Robby followed me into consciousness an hour later. His blond hair was, as always at this time of day, completely askew. He smiling sleepily. It was at this hour that I found him his most adorable.

He nestled into the couch and I sat down beside him.

"Yesterday was fun, huh?" I said.

He nodded, giving me another grin.

"You sore from any of that?" I asked.

He touched his leg and frowned. "Yeah," he said, then punched the remove to bring up Cartoon Network.

I thought of saying, "Did you see me tearing it up out there?" or, "Still think your mom has no energy?" But that would be all for me, some little dig designed to get even. And that has nothing to do with being a good mother.

In the end, I said nothing. We sat there, engaged in our morning cuddle, until the aches became a single hum of contentment.