This is a good time to keep your Hilti near. Also, it might be a moment when you have only 20 minutes of oxygen remaining. Your future self came back in time and burned your arm with a cigar just to get your attention, I cannot believe that you don't have this shit down. Where the hell is your Hilti, man!? You're screwed now, that's all I have to say.
<inattentive future self> Oh no! I have flipped the blue switch instead of the red one! I am locked in this airtight room now, and have only 20 minutes of oxygen remaining! If only I had my Hilti power tool, I could simply cut my way out!
<future -> past -> future self> I said to you on that fateful day - keep your Hilti near! Trust me, you'll know when! I even built, at great cost to my own sanity, a Time Door to facilitate implanting this message in your/my consciousness at an opportune moment in my past/your then-present. I see now that you are not the ripcord in my destiny. :(.