How you should workout
 

Ok first do like sit-ups or push-ups for about 15 to 20 minutes. Next take a long stretch stretch out all leg muscles. Go to the nearest place were you can run or jog. Jog for about 15 to 20 minutes or about 3 miles. Then go home and do more push-ups or sit-ups. :D Trust me it works.

nice one, i just do 100 sit ups and pushups

If you're going to run and are just starting out, don't run at the track. Its too easy to cop out and walk away. Run around your neighborhood if you can. That way as far as you run out, you also have to get back, beit by running or walking.

The problem is everyone has their different techniques. You may find you cannot do all of that exercise, if you cannot then it is a good limit to try and reach.

Yeah its good to keep in mind to do a lot of repetitions of an exercise and set a goal of 10 more sit ups or push ups if you achieved a goal. I found it better to do a sport such as basketball for around 1 hr if running gets to be too much of a hassle. It's a great idea to have someone you can run with or play against.

I have found it easier to have a basketball game when I actually have an opponent :p

Incorporating boxing into a circut training routine is really hard, but rewarding.

Do you need a ring to box? Or can any space work? And how much will equipment cost?

My friends and I were thinking about boxing to see whos the best at it and for the workout.

You dont need a ring, not sure on equipment costs.
The routine is like:
90 secs sit-ups
90 secs sparring
90 secs squatting
90 secs jab pads
90 secs step ups

There is more but i dont really know what the stations are called.

Lol, I do around 200 situps, and 50 pushups a day ( i suck at pushups ) And I also have kickboxing which works me out a lot. :)