I am reading through The Best of A.W. Tozer right now. In a chapter on thought life he says this:
"Anyone who wishes to check on his true spiritual condition may do so by noting what his voluntary thoughts have been over the last hours or days. What has he thought about when free to think of what he pleased? Toward what has his inner heart turned when it was free to turn where it would? When the bird of thought was let go, did it fly out like the raven to settle upon floating carcasses or did it like the dove circle and return again to the ark of God? Such a test is easy to run, and if we are honest with ourselves we can discover not on ly what we are but what we are going to become. We'll soon be the sum of our voluntary thoughts."
Wow! That is really powerful and convicting to me. The Bible says:
2 Corinthians 10:5 (New International Version)
We demolish arguments and every pretension that sets itself up against the knowledge of God, and we take captive every thought to make it obedient to Christ.
God, through His Word, speaks often about our thought life. We can see how the power of thought can work to the good or to the demise of those not only in the Bible but also in our day to day lives now.
This is a lifelong practice! Keeping our mind focused and trained so it (we) can be used to the fullest potential for the Lord.
If you would like to study this further. Go here and type "thoughts" or "mind" into the search engine.