Sowing and Reaping
Psalms:126:5: They that sow in tears shall reap in joy
We all understand the principle of sowing and reaping. No farmers shall expect any reaping without any sowing.
Sowing is hard. It doesn't look right in the eyes: it seems only spending, no earning. But it's an act of faith. By faith you know that when you do the right thing, you'll produce the right result. It takes time, but the reaping will come one day.
Sometimes the sowing stretches ourselves, that it hurts. When you go the extra mile of your normal capacity that it brings tears into your eyes, then by faith you know you'll be rewarded with joy in the time of reaping.
So, this verse is quite simple: no sowing, no reaping; no tears, no joy.
When you understand how it goes, then you'll feel much better even in the time of tears.