When I was 17 I started a course that aimed to prepare people physically for armed forces tests, the running was absolutely brutal to start with but the instructors pushed you until you either finished the run or literally could not do anymore. After 6 weeks of that I could run (not jog, not sprint) 5 miles and barely break a sweat. The harder you train the faster your body will adapt.
your body has to work alot harder when your propeling your sell from standing still but on a treadmill the belt is feed to you so your muscles are working ALOT harder running out side. Also you should start running on a track or some trails rather than running around your block as in street/sidewalk? But it will be easyer on your shins
Since you're outside anyway, I would consider biking. My dad ran alot and even did marathons but when he got older, he paid big time with tore up knees. Let a machine take the abuse and you still get the benefit.
Just an opinion and cautionary tale, not looking for any jogger hate