Doing 25 Press-ups And 25 Sit-ups, And A 30minute Run A Day. Will This Get Me Fit? And When?

If I did what you say? When would I feel fitter a shed a few pounds... Because I'm joining the marines in March, need to get to my limits

I would do it by week or when the exercises get easier for you. If you joining the Marines you may want to double up sooner and increase what I originally stated by two. If I were you I would work to be easily and regularly performing at least 200 push-ups and set-ups and running at least 5 to 10 miles by the time you enter boot camp. This will make your entry and physical stamina at a point that you will probably start at the beginning of boot. My original answer was more for a maintenance level. I do just on a regular basis 100 push-up and set-ups a day everyday. I'm 50 and have worked out my whole life. On top of this I will do at least 4 sets of 10 curls and bench presses. If that helps you. The higher level you attain prior to entering camp the better suited and able you will be. Good luck.