Things to improve

[Swat Runs Train]

Well as far as sit ups and push ups, the more you train the more weight you lose and the more muscle you gain, your numbers should go up quite fast in those departments, in your mile time you may only see a 5 or so second improvement per every few weeks, just keep going.

There really is no surefire way to improve those areas faster, just remember to keep switching things up so your body doesn't get too used to the motions and lower the effectiveness of the activity.