Everyone is different but here is how I started off......

I started off doing 3 miles about 3 times per week. When I first started I could jog about 1/3 mile or so before having to stop and walk. I can now jog a mile, walk about 1/4 mile, jog another mile, walk a 1/4 mile, jog another mile. In 4 months I went from not being able to jog 1 mile to completing a half marathon. It just takes a little dedication and some hard work. Best running investment I ever made was the Rio Sport MP3 player I bought, I would go crazy without it