If I'm backstage as an ASM or running crew, then my black work boots - I have a pair of Magnum Classics which I absolutely love - they have toecaps which are fibreglass or something - not entirely sure what but it means they're lighter than steel toecaps. They're super comfortable, leather so they breathe and I can wear them for 16 hours no worries. Only problem I have is that my current pair, which I bought in the UK, are wearing out and I can't find them here in New Zealand!