Chase your high
I've talked about runner's high in my previous posts (yeah! master in foreshadowing), but this will be only about that and similar states. The thing about runner's high is that you can't be sure you will experience it every time. You might experience it running a 10k, but you can't wrap your head around why you are not feeling blissful while running that 30k or 40k. You can only pray to the running gods to provide you with that feeling around the finishing time. (Here's a description of runner's high for those who haven't experienced it: your entire body feels light, your mental clarity hits its peak, your legs start moving on their own, you breathe effortlessly, and your pace increases.)
I've had a similar experience while public speaking. You are in front of 300 people, but you can't feel anything other than excitement. There is not a shred of nervousness. When others ask how you overcame the stage fright, the only thing that comes to mind is "what stage fright?" but you can't say it out loud because people will think you are bragging.
This also happens sometimes while reading a particularly engaging book. It happened to me while I was 'reading' Shogun by James Clavell. The audiobook was around 53 hours long, but I was fully engaged for three days straight (I just placed my attendance and then continued with this).
When these states arise, utilize them to the fullest extent possible because you don't know when you'll experience them again.