Are you frequently tired? This is the normal effect of exertion, and the exertion can be emotional or spiritual as well as physical. I too was tired from ministry.
Is it an issue in your life that hinders your effectiveness? This is not a reason to avoid exertion, but you need a means of restoration. I did not promise that you would not get tired, but provided for your renewal. They that wait upon the Lord will renew their strength. Your strength only needs renewal if it has been depleted. Exert yourself unto godliness, but do not be weary in well-doing. Come unto me all ye who labor and are heavy laden and I will give you rest.