It really depends on what you want to study and do in life! For example, if you wanted to work in business, you may only need an undergraduate degree (4 years) and then potentially a CPA qualification which can be completed while you work. If you wanted to be a lawyer, you'll generally need an undergraduate qualification (4 years), a graduate qualification (3 years) and have to pass the Bar exam, while you work. Depending on the level of medicine specialty (i.e. if you wanted to be a neurosurgeon, maxillofacial surgeon etc.), you may spend over 10 years in school.
Hope this helps!