First, HS: volunteer with non English speaking kids at your HS and try to become really good at a foreign language (AP level if it’s offered, otherwise find ways to learn and perfect that language).
Take Bio Honors/Chemistry Honors/Physics Honors or AP Physics 1 + AP Bio and AP Chem, AP Stats and AP Calc AB, AP English Language, AP US History and/or AP African American History and/or AP World History and/or AP European history.
Overall, take 4 years of English and Social Science/History, math through calculus, bio/chem/physics, a foreign language spoken in the US, and classes in subjects you love. Most with A’s.
Practice whatever sport or activity that helps you stay healthy - running, pick up basketball, tennis, yoga, rock-climbing, rope-jumping, skateboarding… 
Volunteer with a group of people you’ve never interacted with. Become a leader.
See if you can be CNA certified or start working on being an EMT.
Think of a Plan B.
Explore professionals such as NP, PA, Kinesiologist, occupational therapist.
Then, college.
Get into an affordable college that is neither too competitive nor too easy.
Keep volunteering. Add a clinical component.
Become an EMT.
If interested, work in a biology or chemistry lab.
Do not rush your 1st semester freshman year, take Calculus and Chemistry with lab, add Biology Spring semester only. (You’ll need 5 semesters of chemistry/biochem, only 2 of biology).
Avoid majoring in biology, find another subject that’s a bit less “obvious” and has better professional prospects. Make sure you have a solid plan B.
Keep a light Spring semester Senior year, plan to study through Winter Break then take the MCAT in February and apply then.
If you want to serve as many people as possible, plan to be a pediatrician, dentist, or family physician in a rural area. (Many state universities, from Wisconsin to Alabama, have special programs in Rural Medicine).