If I am diligent (always doing) in the different areas of my life, then I will get everything that I need to done.
It's kind of cool: Mosiah 4:27 is almost chiasmatic in form.
And see that all these things are done in wisdom and order;
for it is not requisite that a man should run faster than he has strength.
it is expedient that he should be diligent, that thereby he might win the prize;
therefore, all things must be done in order.
So we can set "be[ing] diligent" to "not run[ning] faster than [we have] strength," with emphasis on the word "faster"--we could also say, "running as fast as we have strength." Heavenly Father requires our all; no more, no less. And He promises us that when we give our lives, our hearts, and our wills to Him, that we will "win the prize."
Which leads to another scripture, Doctrine and Covenants 106:3, which reads, "And devote [your] whole time to this high and holy calling, which I now give unto [you], seeking diligently the kingdom of heaven and its righteousness, and all things necessary shall be added thereunto; for the laborer is worthy of his hire."
Since coming to BYU, I've begun to really understand that the gospel encompasses all of life--not just the spiritual aspects. So I know that if I work to be diligent in my various roles, keeping the Lord as my focal point and always seeking the guidance of the Holy Ghost, then I will have everything I need and I will do everything I need to do.