Management requires a certain callousness to see the objective without becoming emotionally impacted by the weight of responsibility - there are some tough decisions that won't please everyone and, as the saying goes, it can be lonely at the top. Truth be told, they don't have those executive toilets for nothing (!) and, put simply, it's not for everyone.
Being tired won't help your quest either, as good organisation and a clear head will give you the upper hand. Remember, it takes awhile before you can actually settle into the role; filling someone else's shoes can be as uncomfortable as it sounds.
Also, as for others in health sector, things are not really standard fare at the moment and there are bound to be added pressures to deal with.
Perhaps you could relegate some tasks or have an assistant in the interim - don't beat yourself up about it though, and talk to the internal coordinator/HR about getting some additional help.
After sixteen years you might be suffering burnout, and a change of career (even at reduced wage) could be the panacea and impetus you seek to enjoy yourself once more.
Presently, I feel you are 'comfortable' with the familiar and the thought of venturing out fills you with trepidation - that's fair enough, but you might be surprised at whatever hidden talents you may have within as yet untapped.
Your happiness and quality of life is not contingent on anyone's approval (not even your mortgage provider!), so don't let that sway your opinion of where you want to be.