Very practical and nice read!
Frankl’s quote reminds me of the stoic school of philosophy. The stoics argue that your mind is an unconquerable fortress with walls that can never be climbed from the outside but only brought down from the inside. Your mind is your ultimate bastion in the defense against the amenities of life.
Regarding the more practical part there is another saying that sums it up quite nicely:
If it doesn’t matter five years from now, don’t spend more than five minutes worrying about it.