agree with most every thing everyone else has said.... I'll reiterate, and add a few things.... and my running background is off and on for more than 30 yrs ( plus a miler in HS ... sub 5 min ) 5k's, 10k's 20k's and Shut In Ridge Trail Run here in Asheville ( 19 mi straight up Mt Pisgah ... 6000 ft climb )
first ... goodshoesgooodshoesgoodshoesgoodshoes.... see a pattern there?... New Balance make some incredible good running shoes... so do many other companies... and as opposed to some things, with running shoes you pretty much get what you pay for ... I've used NB for over 30 yrs... bad knees killed my running , not because of the shoes but the yoyo weight control
I vaguely remember something from Runners World mag many yrs ago that claimed ... on avg.... you burn ~ 100 calories per mile, with almost no compensation for pace... in other words, slow or fast the milage is what counts... the way you burn more calories by going faster is that you can go farther in the same amount of time
your routine right now of run then walk the run then walk is an EXCELLENT way to get started...
as one of the earlier posters said ... it's got to reach the point where you feel depressed / deprived / cheated etc if you don't get your run in .... you have to reach the point where you realize you're a bore to others about your running LOL LOL
any time you skip a day makes it that much harder to get back out the next
doesn't have to be run every day .. as stated earlier mix it up