You shall have no other gods before or besides Me.
The best way to determine if God is first in your life is to slow down and ask yourself some simple questions: What do I think about the most? What do I pray and talk about the most? What do I do with my time?
You see, we always make time for what we really want to do— no matter how busy we are. If you want to spend time with God, then you are going to make Him a priority.