This is taken from a post on my Internet Gym site. There is only one purpose to this program; to significantly increase the number of pushups, pullups and situps you can do. It is a lot harder than it looks.

Most physical agility tests consist the following:
Pushup max in 1 min
Situp max in 1 min
Timed 1.5 mile run
Sit and reach stretch test.
(this is the most common test, but by no means the only type)

You will need to start this program as close to 12 weeks out from your test date as you can. Stop this program 3-4 days before the test to allow your muscles to rest.

The Program
Do a set of each exercise: pushups, pullups, and situps. Round down to the nearest 5 unless your max is under 10 (for example 32 would be 30, 48 would be 45, but a max of 7 would stay at 7). This will be your max for that exercise. If your max is less than 10 you will pyramid by 1′s. If you max is between 10 and 20 you will pyramid by 2′s. If your max is between 20 and 40 pyramid by 5′s. Greater than 40 pyramid by 10′s

So the workout would pyramid up to you adjusted max and then back down, all by a set number. Something like this:

Pushups (max 45) : 10-20-30-40-45-40-30-20-10
Situps (max 32) : 5-10-15-20-25-30-25-20-15-10-5
Pullups (max 7) : 1-2-3-4-5-6-7-6-5-4-3-2-1

You will move from one exercise to the next in a circuit, taking a 1-2 minute rest after all three are done. Then move to the next step on the pyramid. You will continue until the longest pyramid is complete. If you finish a shorter pyramid, just continue doing the lowest amount on that pyramid until you complete the others. So in the above example our workout would look like this:

Pushup 10-20-30-40-45-40-30-20-10-10-10-10-10
Situps 5-10-15-20-25-30-25-20-15-10-5-5-5
Pullups 1-2-3-4-5-6-7-6-5-4-3-2-1

You will be working for 13 total sets taking you about 30-45 minutes depending on your pace. You will have completed 285 pushups, 190 situps, and 49 pullups. If you struggle with these exercises then do pushups from your knees, crunches, and chair-assisted pullups. Continue with the easier versions for three weeks, then retest yourself to set a new max on the original exercises.

You should do these exercises three days a week, alternating with running on the other three days (yes you only get Sundays off). Your runs should be as follows:
Day 1: 2-mile run, sprint half a lap, jog/recover half a lap.
Day 2: 2-mile timed run. Try to get under 16 minutes. 13-14 minutes would be ideal.
Day 3: 3-mile easy run at your own pace.

Do this program for three weeks. Then retest your max after a day or two of rest, readjust the pyramids, and start over. This method is a proven to boost your max dramatically in each of these exercises.