A: Both are OK. Left is more common & casual. Right is more posh & bookish.
B: Both are poor grammar. I would omit "during", or replace it with "through", then both versions are fine. Left is more simplistic. Right is more specific.
C: Both are technically OK but the meaning is a bit vague. Consider something like "I'm grateful for being alive in your lifetime" to remove any lack of clarity about what you're trying to say.