I agree that Seneca has a lot of applicable lessons.
Personally, I like Epicurus a bit more.
“Do not spoil what you have by desiring what you have not; remember that what you now have was once among the things you only hoped for.”
“He who is not satisfied with a little, is satisfied with nothing .”
“It is better for you to be free of fear lying upon a pallet, than to have a golden couch and a rich table and be full of trouble.”