"So where could I buy kneepads?" I ask Al, as we emerge from the gym, after a tough session on his part and a half-hour of iron-pumping that's more than enough for me, since I've been out through injury, but he dismisses as barely breaking sweat, you big wimp.
"Homebase, across the road," he says. "Why do you want kneepads?"
"Well I'll tell you, little Sally's coming on great. She's really clever. Sits up and turns her head and rolls over and smiles and babbles."
"You do all that," he says. "Nothing clever about it."
"What she doesn't do yet is crawl," I say. "So I'm going to show her."
"Once you work out how to do it yourself," he says.
"You can mock," I say, as we cross the car park, head into the store, and try to figure out what a kneepad aisle might look like. "But it isn't easy. I did it last week for her, all around the coffee table. Sally thought it was hilarious. It cracked her up. She couldn't stop laughing."
"You always had that effect on females," Al says.
"More often than not these days," I tell him. "It was fine at the time but the next day my knees were bruised. So when I tried to do it again for her, it hurt. Hence the need for kneepads."
"Well it looks like we got two kinds," Al tells me, holding them up in each hand. "This one is large, grey and made of plastic. This one is smaller, green and made of minigel."
"So that would be a different kind of plastic," I say. "We'll have those. Let's go. This will be great."
But later that day, Carol, the physiotherapist, who is always worth listening to, casts scorn on my kneepad plans.
"Babies don't learn to crawl by imitation," she tells me, lying face down on the floor. "Come here, sit between my legs and put your hands on my hips.
"Little Sally is pushing herself up with her arms already," she says. "So what you need to do, when she's in that position, is tilt her hips with your hands, so that her leg bends and her knee comes up. Do it to me, so you see what I mean."
The other thing I need to do, she tells me, is to put something Sally really likes just in front of her, but out of reach. "That motivates her to move forward," she says.
It's a great lesson and I resolve to try it all. But maybe not today, the thought occurs to me, as Carol leaves. "Has she definitely gone?" I ask Susan.
"I don't want her telling me off," I say, reaching for the kneepads, strapping them on and getting down on the floor. "Everything she said made so much sense and I will have a go later, I promise.
"But right now I just want to make Sally giggle some more."