It is fine to be zealous, provided the purpose is good, and to be so always, not just when I am with you. (NIV)
It is always a fine thing [of course] to be zealously sought after [as you are, provided that it is] for a good purpose and done by reason of purity of heart and life, and not just when I am present with you! (AMP)
But it is good to be zealously affected always in a good thing, and not only when I am present with you. (KJV)