Not Sure how Roy F. Baumeister and John Tierney came to be associated with the Teachings of Jesus but in reference to affirmations, psychology is not so engaged with the experience and teachings of spirituality or the spirit.
When the underlying subconscious is plagued with beliefs of difficulty and stress, pasting a good thought on top of a not so good thought does not negate or erase the stress. The body always follows the mind and the mind will need to find a way to step into an experience which is greater than the stress in order to let the stress go. Otherwise it becomes a battle between two opposing thoughts.
The unconscious programs of stress and difficulty in life in any endeavor, and the belief that the positive thoughts can relieve ones self of the subconscious beliefs that have created the experience of those subconscious beliefs, are not dealt with solely on the conscious level.
Often those who have tried on their own to superimpose the positive affirmations withdraw into their old habits.

If one could learn to have a direct experience of the Spirit within, rather than the positive ideal belief and definition of spirit, the experience would lead the mind to surrender the illusions of the stress to the greater reality of the spirit. This is closer to what Jesus taught. Direct experience rather than adopting a personal belief system which conflicts with other personal belief systems.
The spirit is universal and supports all beliefs, but the universality of reality is obscured by the individual belief system which idealizes which belief in the spirit or God is good better or best.

The current state of spirituality reflected by the religions and their need to separate themselves and their beliefs from each other is testimony to this reality.

If it were truly that simple to add a positive thought to solve all issues I think it would have manifested itself long ago. People are not by nature self destructive. Instead because of the ego, people measure themselves against each other and struggle to gain favor amongst themselves and others by supporting individual belief in rallying a majority to protect themselves in their ideal belief about their selves, and their ideas.

Even of one finds a way to temporarily fend off evil the idea that it exists puts them on watch and in fear of losing their ideal to that evil.

Without the direct experience of evil as an illusion of the ego and the ability to See and Experience God in everything, the mind will divide itself thru the beliefs in good and evil and in turn separate itself from others that it sees as part of the opposing force.

No positive thought can erase this fear, in fact every religion and belief system supports this fear based reality.
Where there is no beauty or order to ones relationship with an idea and personal belief there is no God or spirit.
This is however contrary to the idea that God is omnipresent and all powerful, when God has indeed been removed from creation by the eyes of ignorance in superficial beliefs of a personal nature.
I was addicted to the Hokey Pokey, but then I turned myself around!!