The Ninja understanding is that it is often the tricks of the mind that prevent us from realizing that we already live in a world that is sacred, that holds our truth and will meet our needs if we let it. The advice of the warrior, in other words, is to not conspire with the mind that tells us we have lost something and if only it was returned to us all would be well.
If the Tao is whispering to you that you must take on your fatigue by healing your soul, then you have every right to do so, and there is a practice to help you with this:
In many traditional systems of healing, such as those employed by the mountain Ninja, it is believed that illness and fatigue of the soul, no matter what personal or specific form it takes, arises because primal relationships with Earth have been broken. Healing comes from reconnecting with the natural world.
Healers in Japan still prescribe forest walks and meditative contact with trees (regarded as portals for spirit) as cures for depression, which is believed to arise through soul loss. In Japan, there are many sacred trees, rocks, waterfalls, and other natural shrines and power places to which people bring offerings of sake (rice wine), rice cakes, or flowers so they may spend time in the healing presence of nature.