It means that we should fear and not want to succeed at thing's that do not really matter! I understand, it's a little play on words, as when I re-read it for you, I got confused for a second too!
In other words as Believer's set your affections on thing's above, and not on the earthly thing's.Colossians 3:1-25
Matthew 6:19-21 19 Lay not up for yourselves treasures upon earth, where moth and rust doth corrupt, and where thieves break through and steal:
20 But lay up for yourselves treasures in heaven, where neither moth nor rust doth corrupt, and where thieves do not break through nor steal:21 For where your treasure is, there will your heart be also.