"I've never been so grateful for X as when Y happened"

[Tempest]

It can be something you do, another member of the company you're grateful for, the nearest coffee shop, etc.

I've never been so grateful that I don't suffer from stage fright as when an actor ripped his Achilles tendon in rehearsal, earlier this week, and I had to go be the male lead for the first designer run, the next day, in front of an "audience" of about twenty people.

(Aforementioned actor had to drop out of the show and get surgery, yikes!  We're all very sad to have lost him; he was phenomenal!)

[Thespi620]

I've never been so grateful for fight calls as when I was doing the Pillowman.

In one sequence, our Tupolski picked Katurian up and threw him down, on his back, onto the interrogation table. Fight call consisted of this sequence as well as a few other small fight sequences. The 2nd performance night, I get to fight call and the guys are ribbing me about not needing to practice the fights because they "know them cold." I get them to do the smaller sequences, and then we move to the table. In our first run of the sequence, Tupolski picks up Katurian, gets him on the table, and as he steps away the table collapses underneath Katurian.  Immediately, the guy playing Ariel and I bolt off of our feet and rush over to him--he was fine, just a little stunned, and we (luckily) had a spare table backstage which held up when we ran the sequence again, and during all subsequent calls & shows.

Needless to say, I never got any flak for fight call again--and, in fact, two years later, the guy who played Ariel still occasionally mentions it in conversation.