Histadlus Vs Bitachon

Rabbi Lazer Brody from a Shiur "No Bad in the World"

Before you do something you have to do the best that you can, but after the fact you should see all results, good and bad, as coming from Hashem. Just like milk is Kosher on its own, and meat is also, it is traif if you mix them. You should never mix the two. Before the act you should never say, "It doesn't matter how hard I try because it is up to Hashem".

How hard we try is up to us, if we succeed is up to Hashem.