My best advice is to make it something that you enjoy rather than something that you "have" to do.  Start out easy and take it slow.  Perhaps try to alter your route/areas that you run to make it interesting.

 

One other thing to consider.  Save up for the running shoes and if you run every day consider a couple of pairs and alternate them.  Don't skimp on these either.  Running in a cheap pair of sneakers is WAY different than running in a good quality pair of running shoes.  A good pair of running shoes will also aide the concerns about knee pain.

 

Finally, the importance of stretching and hydration are critical.  Take your time with stretching both before and after a run, and stay hydrated.

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