Augustine. Exposition on the Book of Psalms. Schaff, Philip (editor). New York: Christian Literature Publishing Co, 1886. Nicene and Post-Nicene Church Fathers: Series 1: Volume VIII. Re-published 2014, Catholic Way Publishing. Kindle electronic edition, ISBN-13: 978-1-78379-372-3.
Augustine emphasizes that Psalm 131 does not just refer to one person, but that all are called into conformity in it (Augustine Psalms, loc. 340966, par. 1). The humble heart of Psalm 131:1 is, in Augustine's opinion, a sacrifice. It is not offered in arrogance of any sort. Verse two precludes this. We don't focus on things that are "too high" (Augustine Psalms, loc. 340976, par. 3). The dedication of the Christian is to a humble life.
Augustine does bring up the expectation of Christian growth in this context. Referencing Hebrews, he says the Christian moves beyond milk to solid food (Augustine Psalms, loc. 340991, par. 5). In the end he concludes we are to be infants as far as evil is concerned, but adults in understanding. Augustine cautions against pushing people away from the "milk" of Christianity before they are ready. As with an infant, it can bring sickness or death (Augustine Psalms, loc. 341006, par. 6). His expectation is that as we mature we will naturally seek out the food of maturity.
In the end, in our humiltiy we trust in the Lord without end.