Kathleen Norris, in her book Acedia and Me, quotes the Benedictine Mary Margaret Funk in her book Thoughts Matter: "We are not our thoughts. Thoughts come and thoughts go. Unaccompanied thoughts pass quickly. Thoughts that are thought about become desires. Desires that are thought about become passions."
Norris goes on to say, "While good thoughts have the potential to become virtues, bad thoughts are likely to become "bad passions or habits of action."
That got me thinking about the Bible verse that says, "As a man thinketh in his heart, so is he." I think this means that the thought has reached the desire or passion point. We become our thoughts if we allow them to go that far.
I can easily sink into depression if I allow my thoughts to go on unchecked. The best cure I've found for controllable depression is to think of things I'm grateful for, smile at myself in the mirror, and go do the next thing.
I also know that sometimes I think too much. Instead, I should just go on my merry way and LIVE. Too much thinking, for me, is self-absorption. It makes me morose and unproductive.
On the other hand, if I go day after day serving my family with no refilling of the 'living waters' of Scripture, I become angry and want to get away from everyone.
So if I'm going to be consistently happy, grateful, and content, I have to make a conscious effort to keep the balance between working and serving others and refilling my soul with Scripture and quiet. It's hard but necessary.