With What Mitzvah Was Your Lil' Tzaddik Particularly Careful?
My Lil' Tzaddik used to enjoy getting his hands messy. Nothing made him happier than plunging his hands into paint or the food on his plate in front of him and letting the mess ooze through his fingers.
Recently, however, he has gotten very machmir about Netillas Yadayim. Sure he is only two and a half years-old, but whenever he gets even the slightest amount of shmutz on his hands he cries out "Dirteee!" and runs over to the sink in the midst of a meal, grabs his washing cup, and washes his hands again. Perhaps it is his exposure to another boy in his class who is extremely finicky about exposure to dirt or being messy, but my son has now also adopted this predilection for washing his hands.
Lil' Tzaddik plays with two washing cups in the tub each night and it is not uncommon for him to even sit on the couch while holding one in his lap.