Lack of courage is usually due to believing in a limited self-image. What often happens is we create an idea of ourselves from selected memories of what we cannot do. We take these selected memories and we put them all together, and create an image of ourselves that isn't in line with a balanced, clear understanding of both sides of ourselves. Sometimes we project that static idea our ourselves into the future, not realizing the changing nature of ourselves.
So, usually a lack of courage is looking at our insufficiencies, what we lack. By bowing we remember what our potential is. By remembering it, often it will bring up this recollection of the other side of ourselves. Sometimes we remember a time in the past when we were able to face a difficult time. We can remember the Buddha's great potential. We remember the path leading out of Dukkha, leading away from these limited self-images, and towards our human potential. Remembering the Dhamma he taught us, and the path leading out of Dukkha, this helps us to develop courage.
We can also remember that people who started out similar to us, also walked the path out of suffering, and uncovered their deeper inner potential. It's very helpful sometimes, if you haven't read about the Buddha's disciples stories, to read some of them. They have accounts of people, normal people - mothers, fathers, business people, even robbers, whatever - meeting with the Dhamma and being able to purify themselves. People who have lost loved ones, people who meet very similar experiences in life to ourselves, and overcome them. So this helps to develop courage, by remembering all these people down through the centuries who also believed in their human potential and developed the energy to uncover it.
This is how bowing and remembering the Triple Gem helps to develop courage and remember our inner refuge. So when we see the insecurity of life, we don't go on reaching out to try to find security, by understanding that so many things are impermanent and undependable. We draw on our inner capacities to deal with life as it is; and have appropriate responses to it, and try the best we can.
If we can't have appropriate responses to it, then having compassion for ourselves and the human condition, so this softens any feeling of insufficiencies that we have within ourselves. And that in itself is a way out, because we then realize the capacity of these unselfish emotions to take us beyond the small mind focused on ourselves, to the big compassionate mind that is focused on the universal.