8 Watch out that you do not lose what wea have worked for, but that you may be rewarded fully.

Read 2 John 1:8 Using Other Translations

Look to yourselves, that we lose not those things which we have wrought, but that we receive a full reward.
Watch yourselves, so that you may not lose what we have worked for, but may win a full reward.
Watch out that you do not lose what we have worked so hard to achieve. Be diligent so that you receive your full reward.