I for one, always feel like I don't do enough, or wonder if I am missing something bigger that I should be doing for the Lord, etc... Here is a devotion from Elizabeth Elliot that is so fitting.
The God who determined the measurements of the foundations of the earth sets limitations to the scope of our work. It is always tempting to measure ourselves by one another, but this easily leads to boasting or despair. It is our business to find the sphere of service allotted to us, and do all that He has appointed us to do within that sphere, not "commending ourselves."
Paul said, "We will keep to the limits God has apportioned us" (2 Cor 10:13 RSV). Jesus did that--willing to become a helpless, newborn baby, to be a growing child, an adolescent, a man, each stage bounded by its peculiar strictures, yet each offering adequate scope in which to glorify his Father.
Lord, glorify yourself through me and in the place You've set me. Let me not covet another's place or work or glory.