One should not avoid exercise, of course, but learn one's own characteristic sensitivities. Occasionally the opposite effect is seen. Even the most minor of head bumps can worsen the duration, intensity, and frequency of migraines. If you've sustained a head injury of any sort and start feeling a migraine developing, treat it aggressively and early. Most likely it will be a severe attack.
Any sensory stimulus can be a migraine trigger.
If you get sick every time you go a certain place, observe the surroundings closely for sensory stimuli that may be triggering your migraine. When used frequently, tolerance develops wherein higher doses may be needed to achieve the same effect. This is different from addiction. Addiction is an abnormal behavior pattern surrounding the drug such that its use becomes a central part of the person's life. Addiction rarely occurs for migraine use.