When anyone runs, they can hit the ground with up to five times their body weight. As you can imagine, this can be hard on the lower back and joints of the lower extremity, and especially for those individuals with joints susceptible to injury.

Out of caution, I would suggest that you start with (brisk) walking and over time, as you get used to things like, how your body feels as you exert yourself, you can then ease into running.

But since you've already started exercising before checking in with your doctor about your exercise capacity and arthritis (eg. effects of the impact of running + body weight on the progression of knee arthritis), etc., how do you feel after a jog/run, besides a little out of breath? If you don't feel like your heart is going to burst or like you're going to die, then you can probably stick with, or modify, your current program. Make sure to have a chat with your doctor!

Although you're anxious to run, it's important to not increase your goals too quickly (eg. the number of minutes you run per week) and never push yourself -- listen to your body and you'll get to that point eventually.

Also, remember to always do some stretches (eg. for calves, quads, hamstrings) before and after you exercise.