Choosing to leave the field or even the aid-working sector in general can be a difficult decision to make. There may be various reasons why you may need or wish to switch your focus. Personal (rather than professional) reasons are often the driving force: lack of personal life in the field, desire to be in the same location as your partner, interest in starting a family, medical/health reasons, retirement, etc. While you may have decided that it is time to make a change and the reason may be particularly important to you, it does not mean that this period of transition will be easy.
In fact, it can be exceptionally difficult. You may have grown used to experiencing and adapting to cultures that differ from your own and now find yourself in an environment or culture that seems comparitively mundane. You may be accustomed to living in volatile environments where emergencies have kept you non-stop occupied and, now, you may be bored. You may have been using multiple languages in your work environment and, now, only need one or two languages that may include your mother tongue, thus limiting the linguistic stimulation you once had.
Life beyond the field and beyond your aid-working role may seem uninteresting and dull. You may find yourself aching to return to the field or to return to a cross-cultural environment. You may regret that life is not more "exciting" - with non-stop emergencies requiring your urgent attention. You may even find yourself depressed, feeling a real need to be in environments where there is often high stress, constant linguistic and cultural stimulation, and the feeling that you are "needed" as a humanitarian.
Try to recognize that many of us confront these emotions and that it is indeed not easy. Think of it as similar to an "addiction" and acknowledge the importance of focusing on your personal life and the joys and pleasures that you can find within it - many of which you probably have neglected or could not prioritize or even enjoy in the field.
Try to find outlets for your energy - through sports, martial arts, yoga, meditation, writing, etc. Offer your skills, experience and firsthand knowledge as an aid worker to local groups, schools, and organizations. Teach about your experience, educate others about the experience of aid workers and the realities for the individuals and communities with whom you have worked. Offer classes on language, culture, cooking, and other aspects which you've had the opportunity to know through your experience. Volunteer with immigrants, refugees, homeless, victims of violence, and others in need in your new community. And, especially, try to find what is unique and interesting about your current location - recognizing that it is culturally unique and has its own quirks that render it appealing and even stimulating. You just have to open your heart and your mind to find it . . . .