Two key little insights that have helped me through many a tough time in life and my career have nothing to do with technology but have made all the difference time and again. A few short stories...
When I was 16 I had a part time after school job at a local TV station that did live broadcasts. At one point I had a huge amount of pressure placed on my (very capable) shoulders - problem is, I didn't recognize the "very capable" part. Somebody pulled me aside one day, an older, wiser fella, and told me to stick to two rules:
1. Don't sweat the small stuff. 2. EVERYTHING is small stuff.
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All my life everybody always told me I wasn't confident enough. "You just need to be more confident!" they'd say. But what the hell does that mean? What IS confidence, anyway? Is it the way you act? The way you walk, talk, dress? Your tone of voice? You can't fake it of course, so what does it MEAN to "be confident"? How do you just...BE that? It's not a damn light switch, and yet nobody could really explain that to me.
After decades of banging my head against the wall in futility, somewhere along the way (I can't remember where) I heard or read...something...that finally summed it up: confidence means TRUSTING YOURSELF. Trusting not only in your intent, your "goodness" as a person, but in your COMPETENCE, your ABILITY TO ADAPT AND OVERCOME. That you can think on your feet, that no matter what comes your way, that you'll survive, you'll adapt, you'll come out on top, that above all, YOU GOT THIS.
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Come Monday, I guarantee you something unexpected is going to happen. An error is going to pop up, authentication is going to get denied, the proverbial shit will hit the fan.
Plan for that. Expect that.
Then realize: this is not the first time you've faced adversity, and you've won before. You can do it on Monday, too.
Follow rules one and two above, because believe me, YOU'VE GOT THIS if you just TRUST IN YOUR ABILITY TO ADAPT AND OVERCOME. If you do that, it really WILL be small stuff, because you can handle it and a hell of a lot more! Be smart - have a list of contacts at Epicor and internally handy for escalating issues ahead of time, have some links to kb documents available, manuals, etc., maybe some tools/downloads on a USB stick or something - be prepared, not arrogant of course - but stay focused on solving the problem. Any time you're feeling fear, redirect your mind to finding another solution for the problems you might face - find another potential problem and a prepare another solution for it ahead of time (to the extent you can).
Above all, BELIEVE IN YOURSELF!
You got this!