"Do not remember the former things, Nor consider the things of old." Isaiah 34:18
If this passage of scripture is true for us who are believers, why is it that we seem to prefer holding on to all the mess and clutter infecting our minds instead of affirming the process for changing it? I'll admit I don't have the complete answer, and who among us does? I am convinced however that God has provided a way out and away from such a dilemma; what's required is the ability to focus on God's truth about New Creature Strength, and the course of action we need take to have it work for us.
Now the best way I know to illustrate this point is to remind you that as a Bible Believing Christian, you've already made the decision to die off to certain things... What I simply recommend now is that you add those memories for the things that have bound you up for so long now to the list. Some examples as they would apply to the fitness process, since this is our focus (but don't limit this application to just this area of your life) would be things like how tough it was or is to carve out time to exercise on a regular basis.
This has no ill effect for us because our God instructs us to make the most of our time (Eph 5:16, New International Version), so what's best, that extra thirty minutes of sleep or dying off to the notion and trading that time for thirty minutes of exercise unto the Lord? Or, how about eating right? Is there more value in overeating as a vain attempt to satisfy our flesh, or to seek right nutrition as a purposeful act of glorifying God with our bodies (His Temple)?
If your serious the choices are easy, but the how to do it - making the change may be the obstacle... Here's how we overcome it. Case down immediately any memories of how you considered dealing with these counterproductive behaviors in the past by replacing them with the unfailing knowledge that you are a New Creature who is amply armed with more than enough strength and Godly power to become fit; and then move forward in that strength! This is God's Way, developed especially for you!
Well that's all my time for this time; if this subject interests you, please join me next time when I'll share more regarding the awesome benefits of getting and being fit, God's way!