|Since you spent all of that time collecting those Mp3s for your workout at the gym you might as well be able to listen to some of them on the trip there.|
If you have a cassette deck, the easiest way is to use a cassette adapter. If you purchased an after market CD player it just might have RCA jacks on the front or the back where you can attach an MP3 player with an 1/8-inch stereo to RCA plug cable. Some stereos even come equipped with direct line-in jack, which looks similar to a headphone jack, so you can just use a simple 1/8-inch-to-1/8-inch cord. Most original equipment systems do not have RCA or line-in jacks unless you ponied up for the top line option, in which case you’re stuck with an FM transmitter which is may not have quit the clarity but is good enough for most.