A child that is born trusts in his nourishment not realizing the actual source is his mother. As he grows he relies on things according to how strongly he perceives they can support and help him. So he then transfers his trust from his mother to his father. Though he matures he is ignorant of GD's providence in the world, he believes his own abilities come from his talents, so he then transfers his trust to himself.
pg 467
Nefesh Hachaim
A man should dedicate his life to living according to the written and oral law all the while praying for understanding in following the correct path and Halacha.
Gate Four Chapter 7 pg 144
Pirkei Avos
One's soul is a part of GD, working with him to help gain entry to the Next World. This is what the Mishnah is referring to when it says Cheleck, portion, it is his soul.
Alshich on Avos Mishnah Alef pg 4