Why is what I want to do opposite of what I do?

Last Monday was my 31st birthday. I gave myself a 'homeschool holiday' for the day and snuggled into the couch with a science fiction book. My kids were very compliant about this interruption in our schedule, and even cleaned their rooms (with a little prompting from dad). This is all well and good. Little breaks and holidays are needed. The problem came when I found myself very unmotivated the rest of the week. Now, I can think of very many excuses why I did not practice diligence last week, but none of them really matter.
I completely dropped the ball in everything: housework, Bible study, prayer time, exercise, home-organization, healthy eating...the list goes on.
Not too long ago our pastor challenged us to lift the church up in prayer and to fast as part of this prayer time. I participated in a month-long fast during which I did not eat lunch, instead I prayed and read the Word during lunch time. The kids were still in public school at the time so the house was quiet and it was so amazing. I have never felt such an awareness of how incredible the scriptures are. I felt so "close" to God. I found so much motivation to live "on purpose," I saw myself practicing diligence in many areas of my life that month. So I look at the two extremes of those times in my life and wonder if I will ever find a consistency in me. I am grateful that my Heavenly Father does not lose patience with me in my widely oscillating moods, attitudes and commitment levels! O what would I do without His grace?!
So it's Sunday. I'm looking at the week ahead and wondering what will come of it.
I have determined in my heart "to live purposefully and accurately, making the most of the time" (Eph 5:15-16 Amplified) not only will I rejoice in this, but also I will live in such a way as to please Him today. I am not responsible for living everyday perfectly; I am responsible for saying everyday, "Today is His. I will rejoice. I will serve. I will follow."