This is a persistent misconception about running. You absolutely must invest the time to learn
proper form (or more accurately,
unlearn negative habits, because children naturally know how to run), but as an activity it is not inherently dangerous for your joints or knees.
I invite you to read literature on the subject:
1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2556152/?tool=p...
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2743580/
3. https://www.ncbi.nlm.nih.gov/m/pubmed/16932832/
Note: I am not a doctor, and the literature becomes mixed as you study runners with higher and higher mileage per week. The point is that someone with a healthy weight should not be damaging their joints merely by repeatedly running - proper running involves allowing your feet to fall below you, not ahead of you, where the calves and quads can properly absorb the impact and use the "bounce" from the ground impact to propel forward efficiently. Doing something other than this, like landing on your heel in front of your body, forces your knees to absorb the impact.
If you're running 60, 70 or 80 miles per week there may be degenerative effects on joint health, but if we're speaking realistically that is unlikely to happen for someone just looking to get into shape unless they're a few years in and training for something. I run 30 miles per week and have no plans to significantly increase my mileage - my health and fitness goals are rather more "intense" than most people I know and it takes up a lot of my time (looking at about an hour of running workout per day).
If someone wanted to gain the benefits from jogging, jogging to the store or even commuting by running five days a week would be far, far lower than what appears to be the lower bound on introducing joint degeneration.
I'm going to echo the grandparent comment: if you're not already moving and have a favorite exercise (cycling, swimming), I urge you to consider running. Running every day quite literally changed my life. Dieting is a close second. My mood significantly improved, my sleep improved, every physical activity felt better, etc. After a month of consistent running you even miss it when you don't do it.