The Midway CTA station is a bit of a hike from the airport. You have to go through a parking structure and then down an enclosed elevated walkway, through the station and then down steps, an elevator or an escalator to get to the train platform. At Quincy, I don't believe there is an elevator, so you have to go down stairs, then walk about three blocks to the station (including going over the South Branch of the Chicago River). If you have trouble waking, it would be much better to take a cab.