I'm a runner and have to say running every day is perfectly fine...but I'm a runner so I'm biased. hehe =)
There was actually an article published not too long ago that measured the "impact of running" on joints for older runners. The results were good news for us. Runners actually came out on top when it came to things like arthritis etc. Anyway, if I find it I'll post it.
At FIRST you might want to do it 3X a week or so, after you become used to it you can pick it up everyday. I've been doing it every day for a looooong time...BUT of course I don't push it everyday. You can have your interval runs, temp runs, long runs and recovery runs for example.
Intervals are a good way to start...similar to what others mentioned about HIIT. Depending on your ability...you run, jog, walk etc. You can always do let's say 3 min. of intense running (about 75%-85% of your max pace, the pace you would be running at if you were racing) and then slow down and walk for 3 min. or 1 min. or two min. It just depends on how you feel.
That's if you want do more of a HIIT program.
If you're interested in the actual sport then I'd suggest you slow down and go longer. I'd do intervals but not worry about speed for now. I'd do the 20 min.with the goal of MAINTAINING. Your goal would be to be able to run longer, increase you milage over time, add on let's say either 5 min more every time or a mile more every week etc.
I do HIIT BUT I also like to do long runs, wich end up burning more TOTAL calories (the longer you go)...but that's another topic.
Anyway, little by little you can increase your jogging time to say 45 min.
I hope that makes sense.
Lastly (which should go first), what I always tell people that are starting up is make sure you're wearing the right shoes!!! That can make you or break you. You need to be measured by a person who know what they're doing. They should be able to look at your current running shoes and the way you walk to recommend a good pair of shoes for YOUR particular feet...IF you're already wearing the right ones then a GOOD salesperson (who are normally also runners) will tell you as well.
Then there's your form. Make sure you're form is on target, you might be able to go longer and/or faster with proper form. If you're form is lousy then it's going to hurt your breathing, your posture, lead do injuries etc.
Anyway, I could go ooooooooon and oooooooon!
Sorry!
HTH a little!
HAPPY RUNNING!!