If you are lazy, you might want to get quick and fit before you do MMA.

Well you are not just going to be up and go back into the gym to do mma. You'll have to train your body back to way it used to be when doing mma. Your body has adjusted to being lazy.

I suggest doing a lot of cardio and stamina, endurances etc. exercises. You'll find videos on youtube.

It's going to be hard to adjust back at first.

Well you should first figure out what you actually want to train. Although there are "MMA" classes, its uncommon for a fighters core to be "MMA."

Most likely they train in a form of stand-up, and a form of ground game.

Stand-up: Boxing, kickboxing, muay thai, etc.
Ground: Wrestling, jiu-jitsu, judo, etc.

TechLife wrote Well you should first figure out what you actually want to train. Although there are "MMA" classes, its uncommon for a fighters core to be "MMA."

Most likely they train in a form of stand-up, and a form of ground game.

Stand-up: Boxing, kickboxing, muay thai, etc.
Ground: Wrestling, jiu-jitsu, judo, etc.

^^^Yeah, what he said.

Everyone above my post has given great advice. If you aren't in shape right now I wouldn't suggest jumping into a MMA training program. One of the biggest points of beginners classes is being able to pay attention to the instruction, and you can't do that if you are sucking wind or puking. Also, if you are out of breath you will end up getting hurt. The amount of energy that you will expend in a 30 min class is enormous.

I suggest you do the following (Just because you admitted that you are "Lazy"). As Techlife mentioned above find out what discipline you want to follow. I would then start a basic regime of cardio and upper-body workouts. A major area you need to start on is your Abs/core. A tremendous part of any of the named MMA types is core/ab strength. You don't need to spend any money doing this, just design a workout at home. I suggest doing that for 4 weeks (Depending on how you feel).
Cardio
Run - Alternate long, medium and short distances along with speeds.
At least once a week (At first) I would try to run stairs (You can use the local high school football stadium)
At least once a week do timed sprints (either around the track or using telephone polls on the open road Sprint - Jog - Sprint - Jog...etc). This will improve endurance and speed
Swim (if you can find a cheap place like a YMCA or community center)
When you swim alternate between doing long slow laps for distance and speed sprints
Tread water (alternate using only your hands or feet)
Use a kick board

Work out (all can be done without equipment)
Push ups (alternate between regular sets and timed events (1 min, 30 sec....etc this will help your muscle endurance)
Abdominals (always alternate your exercises to work on different muscles)
Pull ups
squats
dips
Daily Dozen (a set of 12 exercises that you do one after another)

Part of the routine I would suggest is doing the following before bed every night
4 X 25 push ups
4 X 25 sit ups (or other ab exercises)
If you can't do 25, do 10. Do that for a week, you will see improvements. After that do it 3 X a day (if you can)

If you are going to go into Judo or Aikido I would do some wrist exercises. For the first 3 to 6 months you will learn how to fall after being thrown and your wrists will be sore as hell.

The key is to start out slowly. Do it smart and don't get into a hurry.
Make goals and track your progress

Just my .02

Good luck


Groovy

I recommend doing speed bag, and cardio helps with boxing/MMA