any runners?

Ok so alot of you obviously run. I want to start running once my arm heals alittle more. Buuuut my running endurance is horrible at best. Do I just start running like 1/2 mile a day then step it up? or just push myself to the calapsing point? I use to be a thrower on track. we ran 1/2 mile a day for warmup. at first I was winded after 1/4 mile. after a few weeks I could pass the runners. So yeah, should I just start off at like 1/2 mile a night then work my way up?