Whenever I come across a familiar verse like this one, I like to look at a few different translations to give myself more to meditate on:
Every way of a man is right in his own eyes: but the Lord pondereth the hearts. Proverbs 21:2 KJV
People may be right in their own eyes, but the Lord examines their heart. Proverbs 21:2 NLT
We justify our actions by appearances; God examines our motives. Proverbs 21:2 MSG
You may think that everything you do is right, but remember that the Lord judges your motives. Proverbs 21:2 GNT
There are several more translations, but just those 4 can give us a lot for our hearts to consider!