How do I know if medical school is for me (assuming I am able to get in)?
You need to shadow some physicians so you can see what their working life is like. You also need to volunteer in a healthcare setting to see if you can deal being around sick, injured, disabled and chronically ill people and families all the time.
Don’t limit your volunteering to just hospitals. Also consider volunteering at nursing homes, group homes for the physically & mentally disabled, rehabilitation hospitals or centers, summer camps for handicapped children & adults, stand alone clinics (like Healthcare for the Homeless or other urban public clinics), suicide or sexual assault crisis call lines. All the people you will come into contact with at these sites are your future patients.