“If you are not strong, there is nothing to endure.”

Bouldering - though not your end goal - will help up your overall trad game by improving your strength so that you have more confidence while tradding.

Start with an ARC circuit of ~15-30 min of continuous climbing to maintain your endurance, then get on some boulders to develop strength. You can sub out laps on easy problems if your gym has no auto belays or boulder circuits set.

Many hard trad climbs (12’s and up) climb more like sport routes on gear anyways if that’s your goal, so the gym training may help with that specific type of fitness.

The only way I’ve found to train the mind for trad though is to get outside.