In the LORD - The Greek describes us being locked up inside Jesus Christ. 

Paul is saying we have actually been placed inside Jesus Christ; He has become our realm of existence and the place of our habitation.  Because the power of God is also located inside the LORD, and we are also located inside the LORD, it means we are constantly rubbing elbows with this divine power on a minute-to minute basis.  

Finally, my brethren, be strong in the LORD, and in the power of his might.  (Ephesians 6:10)