You Don't need 2 hours at the gym. In fact, I'd argue that if you're spending more than an hour or so working out, there may be a problem with your training. Too much talking maybe. Too much narcissistic mirror watching, or messing around on your phone. I cannot relate. Training is sacred, and when I train I'm all about getting down to business, being focused and getting something specific done. With just a couple dumbells and 20 minutes, there are endless possibilities to hammer out a great, productive session.
Below is one example from my YouTube Channel (SupaStrong). I was able to hammer this out in 20 minutes (5 x 4 minute rounds), while building up a decent amount of volume, and also giving my heart a workout similar to running a moderately fast 2-3 mile run. I've attached my HR data from this session to demonstrate.
You can see below that along with a pretty decent amount of lifting volume, I also had my heart rate in the upper training zones (150-168) for about 13 minutes. I also burned over 330 calories (likely significantly more than that considering the "afterburn" effect of intense sessions).. in just a 20 minute workout.
Check out 20 Minute Workout #2 COMBAT READY
Notice how each interval creeps the heart rate up higher.. this reflects the fact that when you train in intervals, each interval becomes more and more aerobic.. the body becomes increasingly more dependent on the aerobic system to keep you moving.. this is as true for interval sprints as it is for lifting like this.
Building these types of sessions is pretty simple. Choose 4-5 compound movements, using whatever implement you have available (kettlebells, dumbells, small children).. and choose how much volume (reps) you're going to perform for each. I always choose at least one movement that will really drive my heart rate up, such as clean and press, to really challenge my conditioning with a full body movement. The possibilities are endless.
I highly recommend training with a heart rate monitor. It can be a game changer, but I'll save that for another article. Till then, go get some!