1st Obstacle:
Finish a 3 or 4 year undergraduate program at a university/college and get decent grades to even be eligible for review by the admissions committee at the medical school. As a rule you must have a minimum of approximately GPA of 3.5 or 87%. The minimum GPA varies but to even have a modicum of success you need to aim for that GPA preferably much greater. The courses you should concentrate on are molecular biology style courses which includes genetics, cell physiology, biochemistry, molecular biology etc as well as physiology. Make sure you choose courses that will give you not only a good grade but also something that will help you to understand medicine further.
2nd Obstacle:
If you want to attend a US or Canadian medical school you must also do the MCAT exam (Medical Collage Admissions Test). The MCAT itself is not overtly difficult but some people have more difficulty then others.
3rd Obstacle:
Applying to various medical schools in which you give them various information including your grades as well as MCAT scores. Furthermore, you also usually write a short essay explaining why you would be a good candidate as a medical student. You finally get an interview and must impress them sufficiently to then be accepted.
4th Obstacle:
Finish 4 years of medical school. First 2 years are done in a classroom where you receive a great deal of theory and little actual clinical experience. After the first 2 years you write a medical licensing exam which is either the USMLE Step 1 (United States Medical Licensing Exam) or if you are in Canada the MCCEE (Medical Council of Canada Evaluating Examination). After SUCCESSFUL completion of your appropriate