Chirrut goes into heat just before the mission. He'd thought those were all behind him at his age (he's stated as 52 in the visual guide)...but apparently not. Baze of course, helps him through it.

+if they have always wanted a family but haven't conceived. Chirrut sees this as one last shot at it, Baze thinks it's a kick in the teeth seeing as they're about to die anyway

++they survive and the IMPOSSIBLE happens.