I just tried out a great interval training workout the other day and found it quite effective.  Personally, I hate running.  It is long, boring, and even though I am feeling great afterwards, it just is not fun.  I find that interval training, on the other hand, is a bit more exciting, and it helps me prepare for martial arts conditioning that I have not achieved yet.
Interval Training
After warming up properly and stretching, jog at a comfortable pace for about one minute.  Immediately run as fast as you can for another minute, and finally end with a one minute walk.  Attempt this routine for fifteen to twenty minutes.
Mix it Up
After a while, that can get pretty monotonous and boring.  Instead of one minute, go for two minutes with a one minute spring and a thirty second walk.  If you are really adventurous, add or find obstacles, such as walls to jump over, fences to scale, or steps to run up.  If you want good ideas, look at the sport parkour.  These guys make running fun!
If parkour is absolutely not your thing, after all it is not for everyone, mix up your running routine with jump rope, manual resistance exercises, and/or shadow boxing. Either way, running can be a fun part of your workout.