We learned in Boy Scouts to do something about breathing and bleeding first. But even in the midst of breathing difficulties, it may be helpful to stay aware of what is going on in my mind and mood. I read recently of a soldier trying to not black out while helping a wounded buddy. He had learned "square breathing", a simple pattern of breathing in to a count of 4, holding breath for a count of 4, exhaling to a count of 4 and again holding the breath for a count of 4. It was felt that concentrating on keeping that pattern going while tending to his wounded comrade kept him conscious and effective.
But after that experience, after he got some help and was in a hospital, would be a good time to create positive feelings if they didn't arrive naturally. Positive feelings can be overdone. I suspect evolution and life in general is smarter and richer than any simple formula I can cook up. Just as I am not attracted to continuous drugging, I am more interested in open-eyed, full-frontal participation in whatever feelings (and events) that emerge from living and loving.
Still, it is nice to practice creating positive feelings when I have a moment. Eric Barker reported someone's method of thinking of someone I love and the checking how many ways that someone and my love might not have gotten together. Many Zen, Buddhist and happiness coaches and gurus advise awareness of THIS moment. Bleeding or not, I will never see THIS moment again. Hats off to it! Its special quality, its preciousness, its particular and peculiar flavor of yuckiness. (It is hard to get good quality yuckiness these days. Not like when I was a kid.)
A major key to emotion construction is careful awareness, eye and ear and smell and touch and body sensations. We have 11° below zero outside just now and the merry wind takes that oppressive heat away quickly so it actually feels more like -24°. It is a sunny, bright day. Imagine our gratitude for good clothes and heat and calories.