My Fitness Journey

So I've decided its time to get back in shape this week... I've always been a fairly fit person. I can usually keep up with the mediocre athletes in any sport. I have hit several highs and lows in training by myself. I've ran 60 miles in a week, I've walked 30 miles in a week, I've done over a hundred pushups in a row, I've done a hundred pushups in two minutes, I've done a thousand ab exercises in a day, etc etc. Although fairly notable these aren't fantastic. Yeah I have an 8 pack, yeah it could be better. But that's not what its about this time. This time I want a basic level of fitness that I will keep the rest of my life. Cardio is so easy to lose after just weeks. I started training this week monday I ran 1.5 miles in 12 minutes stretched for a couple minutes and ran 1.5 home in 13. Pretty pathetic times.... but I wasnt winded the whole way or anything. Tuesday my girlfriend and I got in an argument so i went on a run while she cooled down, just a mile nothin fancy didnt time it. Wednsday I ran 3 miles 12 there 12 back, not bad, not winded, but still failing the PFT my goal is 18 minutes for three miles, ive ran it with pants and boots in 21:30, I know I've ran it in less than 20 because it used to be my evening run. But now I've got no base level of fitness. Yeah i can still do a thousand ab exercises but theres little... function to it. I want a level of fitness that will benefit my life. I also work at fedex so i have decent upper body strength from moving retarded shit people mail around... mufflers vehicle frames, boxes of nails, etc. I've also started playing a game I call 200's, it looks like this,
day 1, odd, do 200 pushups in as few sets as you can
day 2, even, do 200 pushups throughout the day
day 3, odd, do 200 pushups in as few sets as you can
etc
day 10, even, do 200 pushups throughout the day
day 11, rest
day 12 rest
day 13 rest
day 14 see how many pushups you can do in a row or in 2 minutes
2 minutes is what the military tests you on, 2 minutes of pushups and situps, you do 1.5 2, or 3 mile run, and the Marine Corps does pullups instead of pushups.
I also want to get back in shape for fighting MMA, It's fun i like it. Excuse my I, and i, throughout this, sometimes I'm lazy and don't hit ' or shift for my words.
Currently I'm on day 4 of 200's...
Any suggestions for my workouts?
I'm looking for a killer total body core workout to do after my run,
right now i just do a mix of puhsups situps pullups dips mountain climbers squats lunges jumping jacks, things like that, i injured my back so i cant do mountain climbers or bear crawls or stabilizers right now. :(
off to the chiropractor to see what i did to my back.