The good news: You can do metabolic conditioning training in many ways. Here are some of the most popular ways you can incorporate metabolic conditioning into your training plan:
Circuit training
Circuit training involves moving from various exercises and oftentimes equipment (body weight, barbells, kettlebells, and so on) with little to no rest in between. For example, a simple method is to move from five push-ups to five dead lifts to five pull-ups to five goblet squats without any rest between the exercises.
This method isn't an appropriate way to strength train, because fatigue will greatly limit the amount of weight you're able to lift. Fatigue is your friend for metabolic conditioning, but not for strength.
Circuit training is inherently fatiguing, which is pretty much the point. If you want to give circuit training a shot, start out by selecting three to five simple exercises (such as the kettlebell swing or the goblet squat) and perform them either for time (15 to 30 seconds each) or for reps (5 to 12 is a good range for metabolic circuit training).
But whatever you choose, you must stop immediately if your form starts to sour. Any sort of Olympic lifting (such as the clean, jerk, and snatch) wouldn't be a good movement to include in circuit training, because these lifts are highly technical, demand a high level of concentration, and quickly fall apart under fatigue.
Interval training
Interval training involves exercising at various levels of intensity. A popular method of this is interval running, where you alternate between sprinting, jogging, and walking for a specified amount of time. For example, you can follow the sequence of 10 seconds of sprinting, 20 seconds of jogging, and 30 seconds of walking, repeated for 15 to 20 minutes.
Complex training
Complex training, or more specifically kettlebell complex training, is similar to circuit training in the sense that it strings various exercises together (two or more), but does so using only a single instrument, such as kettlebells or barbells. What's unique about the kettlebell is that its compact design allows you to flow smoothly between movements without having to change weights or devices, which means you can get more work done in less time.
A kettlebell complex can be something as simple as combining kettlebell swings and goblet squats into a ladder format. For example:
2 kettlebell swings
1 goblet squat
4 kettlebell swings
2 goblet squats
6 kettlebell swings
3 goblet squats
8 kettlebell swings
4 goblet squat
10 kettlebell swings
5 goblet squats
Run that entire ladder without setting the kettlebell down and you'll quickly understand why kettlebell complex training is so effective for training metabolic conditioning and developing work capacity.
You should train metabolic conditioning twice per week, with an optional third session. Remember, do your metabolic training after your strength training, never before it (because you don't want fatigue to interfere with the quality of your strength training).
When deciding what specific type of metabolic training to do, you will benefit immensely by just starting with interval running.