If your goal is efficiency, then adding weights to your routine is paramount. Using body resistance is fine, but the results you want will take longer to appear. I work fulltime so my lunchtime workouts have to be fast, but I don’t want to waste my time either.
In order to get the most out of my short break I forgo the treadmill and hit the weights. I train opposing muscle groups, also known as agonist-antagonist training, which means if I work on hamstrings, I also do quads. Balance is key in all things, and that certainly applies to weight training.
I train opposing muscle groups every other day, but I focus on my core every single day. Your core is crucial for assisting in all other exercises, not to mention everyday activities. Using a 15-20 lbs dumbbell or kettlebell will skyrocket your core strength, and you will immediately notice how much better you feel sitting at your desk, bending over to pick something up, or even walking down the street. So make sure you’re adding weights into your workouts–even 5 lbs will make a difference, and enjoy the changes to come.