The Mitzvah without Kavanah

Deuteronomy 24:19-22
This is another reminder to take care of others who are less fortunate than you are. If you forget some in your harvest - do not go back to get it - leave it for the poor.

Why not just harvest it and give it away? This helps those in need maintain their dignity to collect their own food.

Side note: Rabbi Marder read part of Keats poem Ode to a Nightingale

Thou wast not born for death, immortal Bird!
No hungry generations tread thee down;
The voice I hear this passing night was heard
In ancient days by emperor and clown:
Perhaps the self-same song that found a path 65
Through the sad heart of Ruth, when, sick for home,
She stood in tears amid the alien corn;
The same that ofttimes hath
Charm'd magic casements, opening on the foam
Of perilous seas, in faery lands forlorn.

As it refers to Ruth as she harvested from another's field.

This led to an interesting discussion on about Heschel's commentary on Religious Behaviorism, where you will do things without knowing why. And noting that this particular mitzvah that is more about forgetting than remembering.
Hirsch points out that the forgotten sheath is not yours alone and that you must share with those in need.

Social Welfare is not personal sentiment. It is an obligation.

It will create a sense that it is not needed to 'grab every cent from the harvest' and inspired proverbs that remind us 'do not rob the desitute'.

So it can be a mitzvah sometimes to forget, if it helps those in need.