CNA: While some CNA programs last a year or more (and with good reason - CNA's have a lot of responsibility!), there are some programs that last no more than 4 weeks. For example, anyone over 16 years old and living near Philadelphia can take a 4 week Red Cross CNA course. You can easily fit that between high school or college courses in your summer off and have a reliable way to make money throughout the coming school years. You can also check out the bottom of this webpage for free CNA courses in your state.
EMT/EMS: Check out your local Community College for EMT courses. While EMTs do not have the breadth of responsibility that Paramedics do, you can quickly get your EMT/EMS certificate and begin working in emergency medicine while deciding on your next step. For anyone living in NYC, Laguardia Community College offers a free, four month program to become a certified EMT. They also provide academic support and job placement assistance - what a great way to get to work!
Medical Coding and Billing: Online courses for medical coding and billing can be easily found by doing a quick Google search. For example, DeVry offers a 3 semester course, and AACP has an 80 hour course that can be completed online to prepare you for the CPB exam. For stay at home parents and people without reliable transportation, having a medical coding and billing certification could be a great option, because there are quite a few billing and coding positions that can be done remotely.
Hopefully these help give everyone some ideas for how to join the healthcare field without needing to invest 2-4 years in education. The great thing about all of these options, is they would allow you to get a paying job while completing more advanced degrees (for example, a Nursing degree).