It is related (Likutei Dibburim, Chelek 5) that a chasid once told the Riyatz of Lubavitch zy”a that he sometimes felt like he didn’t have enough time to daven with peace of mind. He asked if he could instead fulfill his obligation of tefillah by learning Sifrei Mussar.
The Rebbe told him, “There are several ways a person can do hishtadlus for parnassah. Some people open a store or business. Others are unable to make a living, so they go around asking for handouts. They both are doing hishtadlus and they both will be helped by Hashem. The difference between them is that if the businessman is provided with success by Hashem, he will be able to live like a wealthy man. He will have plenty of fine food, a nice house, fancy clothes, and enough funds to help others in need. If the man asking for handouts is helped by Hashem, he will still only have enough for some salted fish.
So too, if a person exerts himself to daven properly, he could rise to lofty spiritual heights that he otherwise would have no connection to. On the other hand, if a person exerts himself to learn Sifrei Mussar, Hashem will also help him but he will never be able to achieve the “riches” one can obtain through tefillah.
