Kinetosis: popularly called motion sickness. How can I prevent it?

Motion sickness is something I battle with all the time.
Motion sickness is feeling sick while traveling either on land or air or sea.
It comes with symptoms such as dizziness , nausea, headache, cold sweat, irritation and most times loss of appetite
Most times am irritated by smell and loss of natural air. How can I prevent motion sickness? it can be so embarrassing because I see myself vomiting inside the bus and this has brought phobia for travelling.
Please how can I prevent motion sickness?. this it's a battle for me