You should get friends who want you to lift with them and not run with them. Or you could just tell your friends "no thanks, that's gay."
If you want to start training then I don't suggest building up to it gradually. I would do a dead sprint 5K on day one and see how far you get. Do it again on day 2 and see if you can get further.
Ok I'm kidding, but honestly, I don't really have a long distance running program for you off the top of my head, but your basic strategy is correct. Start with a combo of walking and running for 5K's and then, over time, you will reduce the walking and increase the running. You can do this by using time, or using landmarks/distances. Also, I think there is a phone app called "Couch to 5K" or something like that has a detailed program in it that starts with short walks.