The Midrash describes how Ya'akov fled to Charan without a penny in his pocket (according to Midrash all he had was taken by Elifaz). En route, he thought about the contrast between his situation and that of Eliezer, who years earlier had made the same journey to Charan with an entourage of camels laden with gifts and goods as proof of Avraham's wealth. Ya'akov thought to himself that the situation seemed hopeless. He immediately reminded himself, "Ezri mei'im Hashem osei shamayim va'aretz."
The meforshim are bothered by Ya'akov's "hava amina" -- doesn't having bitachon preclude there ever being such a thing as a hopeless situation? (The easy answer to the question is why not? Shema yigrom ha'cheit...)
The Maharasha (Sanhedrin 95a) writes that the word "ozer" in Tanach always means (and I know you are going to get out your concordance to check) to help a person help him/herself.
I once heard someone explain that the phrase in our davening, "Melech ozer u'moshi'a u'magen," refers to three distinct types of aid. When Hashem is ozer, it means we have to do our part. He is there to help -- that's what ozer means -- but we need to take an active role in our own deliverance. Moshia means Hashem saves us without our having to do anything -- Hashem yilachem lachem v'atem tacharishun. Magen means a shield -- Hashem is there to protect us from trouble before it reaches us so that we don't need him to be a moshia or an ozer after the fact.
(Parenthetically, your spouse is called an eizer -- eizer k'negdo -- from the same root as ozer. When it it time to take out the garbage, do the laundry, or wash the dishes, you may want a moshia to rescue you without your having to lift a finger, but that's not the relationship the Torah has in mind.)
Returning to our original question, the Ksav Sofer explains as follows: Ya'akov was forced to flee his home and run for his life. He was forced to fend for himself in Lavan's home. One might have had a hava amina that something is off -- where is Hashem to come to the rescue and help Ya'akov avoid such trials? Ya'akov reminds us that "Ezri m'im Hashem" -- even when we have to make our own efforts, Hashem is still there and we are not alone.