Galatians 6:9

The weariness named here is a specific kind, and it is not the weariness of doing wrong.

Paul writes about growing tired in doing good — which means the fatigue in view belongs to people who are already doing the right thing and have been doing it for some time. That is a particular exhaustion, and it does not come from failure. It comes from continuing without visible result.

And the agricultural image explains why. Sowing and reaping are separated by a season. The gap is not a malfunction; it is how growing works. But it means there is a long stretch in which the work has been done and nothing can be seen, and the person doing it has only their own memory of having planted.

In due season is the phrase that concedes the difficulty. Not soon. Not on request. In its own time, which is determined by the crop and not by the farmer's patience.

The last clause is the only condition, and it is minimal: if we don't give up. Paul does not require the work to improve, or the sower to feel differently about it. The single requirement is not stopping.

Which is a mercy for anyone doing something good that nobody has noticed. The verse does not ask you to be encouraged. It asks you to still be there.