I'll suggest some myself, based on various parts of the story:
Parnassah comes from Hashem.
Even if you work harder, you won't make more than Hashem allots to you. [Not, say, Everyone gets exactly the same amount.]
It doesn't help to work on Shabbos.
We are supposed to be satisfied with what we need.
Enjoyment doesn't come from the taste, but from our ...
There are a few things that the story of the manna teaches me personally:
The Gemara teaches not to worry about what will happen tomorrow (Yevamot 63b):
Do not suffer from tomorrow’s trouble, that is, do not worry about problems that might arise in the future, as you do not know what a day will bring.
Therefore, R. Eliezer Hamodai says (Mekhilta d'Rabbi ...