The first real challenge of your resolve will come when shit -- not just one piece of shit, but lots of shit at once -- goes wrong.
There's no need for resolve when things are running smoothly and everyone is loving what you do. The challenge comes when plans go way too left and you're alone to deal with it.
So if you're in that spot now, this is what makes you who you're gonna be. Stand your ground or run (back) to where it's safe?

If you're not in this position, mentally prepare yourself for the day before it comes. You can't much physically prepare for something unknown, but resolve, like that feeling-good swagger, is not physical.
It's all mental.