Starting C25k at week 4

I just completed Week 4 Day 2 this morning myself! On my program, there is one more day in Week 4, so i'm not sure why you're jumping ahead to 5 just yet, unless your program is structured differently.

The knee pain concerns me a lot. Don't ignore it. You shouldn't have joint pain while/after running; sore muscles, maybe a little weakness; but not pain.

I'm new to running, so take my advice with a grain of salt, but i wonder if you maybe jumped too far into it, too quickly. Your cardiovascular health may be good enough for Week 4, but perhaps you are over-working your knees. Part of the slow introduction to running that i liked about C25K is that my legs weren't ready. Each time you run, you stress your bones, muscles, and connective tissues. During recovery days, they respond by getting a little bit stronger, to be ready in case you stress them again. I have felt my legs getting more fit, and i've noticed that i feel a lot better and a lot stronger after completing each session.

While it might feel like a set back right now, my recommendation would be to start over at Week 1 Day 1. Be really attentive to your joints and overall body aches and pains after completion. if you don't notice the knee pain, keep going. At the end of the program, you'll be knocking out 5ks, and a few lost weeks will be water under the bridge.

If you do notice the knee pain doing Week 1 Day 1, you might want to look into your form. Lots of good advice on proper running form and breathing, from lots of friendly, knowledgeable folks on these forums.

Agree with the above, the pace is structured to start slow, and the built in rest days are very important. You can start at week 1 or 2, and try running faster on the run parts to get your heart rate up. I wish I had done that when I started, as I had to go back and start over running faster to build up my speed. Make sure you stretch before and after your runs, and good shoes are important. My joints start to hurt when my shoes get too many miles on them. good luck to you!

If yo're getting knee pain I wouldn't push forward if I were you. DEFINITELY don't ignore knee pain. If it seems easy but you are getting joint pain, the probably your heart and lung fitness is ahead of your joint and muscle fitness.

It takes some time for your joints to adapt to running. I suggest starting at the beginning of c25k, even if the first couple of weeks seem super easy. They start you out with very little running on purpose, to ease your body into it and let your joints adapt. There's no hurry, taking a couple extra weeks is no big deal. Don't worry about pace. At all. The biggest mistake beginners make is going too fast at first.

Also I strongly suggest going to a dedicated running store and let them fit you for some good running shoes. There are several different kinds and you need to get the right ones. Good running shoes aren't cheap but a great investment in running without injury.

Good luck!