[Wait, hold on a moment. Three years ago? Pick a birthday? That was... a strange choice of words even for someone like him, not necessarily the birthday part but the age. And then everything else combined with that isn't exactly adding up to him.

She can sound older but then there's other bits that are... very much childish. Something isn't right here and it's not going to leave him alone until he finds some way to consolidate the information.]

Why would you need to pick a birthday? I suppose if you didn't know when you were born... [He leaves that specifically open ended to see what she might do or go with that information. As for the rest, well.]

It would still be a lot of upkeep that would go with a body of water, particularly something of that caliber. But, I'm assuming, that isn't something anyone has to do. [This train is odd, he's concluded. And he's too tired to question how it even works.]

Swimming is a fairly good way to get exercise in without putting too much strain on the joints and muscles of the body. While simultaneously helping build them up to get to something that has more impact in the future... [He can't help but think in medical, sorry, Potato.]