I've been on an exercise and diet plan for the last 5 months that has me eating very specific foods at very specific times of the day.
When I started it, my trainer had me pledge to 3 months of rigorous commitment. After following his plan to the letter for a few weeks, I thought I deserved some kind of reward (hear: cheat day). What he wrote back hit me quite abruptly: "You have to eat right 100% of time."
"Really?" I thought, "Is there NO grace?"
Similarly, Paul writes something in Colossians 3:17 that hits most people abruptly: "Whatever you do, whether in word or deed, do it all in the name of the Lord Jesus."
I think this text is one of those that we read, but don't believe is possible. We quote it, study it, hear sermons on it, maybe even like it, but we don't do it. We think, "Really? Is there no grace?"
Here's something I've learned from my diet: Thought I like playing the martyr, eating right 100% of the time is not impossible, and is not torture. It is actually easier to maintain the discipline than when cheating every now and then. And the "grace" that comes from giving 100% is the result that I get when I follow the plan as designed.
Be honest: have you ever tried following this verse as if it's possible? Or have you hidden behind your interpretation of it to protect yourself from the cost it demands?
I challenge you to believe that this verse means for you to do what it says.