One is obligation is to put as much effort as needed to be naturally successful. After that if H'shem wants to give him more he will do so without "any trouble or effort provided he relies on GD for it and does not overly pursue natural means or rely on them in his heart."
pg 409
Nefesh Hachaim
The Gemara explains, if one believes H'shem "overlooks" the wrongdoing of a sinner, he will have GD, Chas Vishalom, "overlook his life" for that attitude is incitement for others to sin.
Gate Two, Chapter 8 pg 86
