The verb necessitate shows that something is necessary or needs to happen, as when a sweet tooth can necessitate a trip to the store for a triple-scoop ice cream — which will necessitate a trip to the gym.
Synonyms for necessitate are "require" and "force." Although what's required may be serious, necessitate also just labels things that follow naturally from one step to another. A dead car battery might necessitate a long walk home, or your completion of skills tests might necessitate moving up to the next level. Necessitate commonly replaces "need" when doctors talk about treatment, so while your scraped knee might need a big bandage, it may "necessitate treatment with antibiotics" if you go to a clinic.