Rest Is God's Law
Don't work so hard that you miss your time with God. Rest is important for your spiritual and physical life. The need for rest can't be ignored; it is a law of God. Just like the laws concerning eating, sowing, and reaping, we cannot break the principle of rest without paying the price of disobedience.
Paul sent Epaphroditus home saying that he came near death through working for Christ (see Philippians -30), but God had mercy on him and spared his life. Find time to be still on a regular basis. It is in moments of rest that you are most likely to hear God speak to you.