Think of something you desire that you know, expect, or hope to obtain. Who do you know, expect, or hope will cause you to obtain it?
I'd say the choices boil down to "humans" and/or "God." (Angels act as agents of God, and if you're counting on a demon to obtain something you desire... that's a different post.) (You might also know, expect, or hope to obtain something via impersonal natural causes, or even just chance, but I'll treat both as special cases of God's actions.)
Imagine a little compartment in your heart that provides the fuel for your knowledge, expectations, and hopes of obtaining things. In general, it will contain a mixture of two fuels, reliance on humans and reliance on God.
Now, on which of these fuels do our hearts run better?
Reliance on humans leads to anxiety. Reliance on God leads to peace.
But it's more than that, I think. In a sense, reliance on God is peace, the peace of God that surpasses all understanding. To put not your trust in the children of men, in whom there is no salvation, instead to have your hope in the Lord your God, is to have a well-ordered heart, and as you know peace is the tranquility of order. And the very experience of God's peace, the presence of that grace in our hearts, enables us to grow in reliance on Him.
Of course, the reliance on God to which we are called doesn't amount to quietism, nor is God's peace a kind of torpor or dormancy. In practice, the two fuels I've pictured above mix; we rely on both God and ourselves to obtain food, for example. But the proper reliance on ourselves and other humans is conditional on and secondary to a reliance on the Lord, Who made heaven and earth.