Certain activities can cause nausea and even vomiting in sensitive people. This is probably an autonomic response to exercise, high altitude, fatigue, distress and a variety of other things such as looking at a bloody accident. The best therapy is rest and reassurance and removal from the cause. An antiemetic or an antihistamine might help, as would an atropine-like drug, but side effects may be unacceptable. Ginger is a well known anti-nausea herb, and it can be taken in a variety of ways such as in the form of a sweetened tea.