the POWER of CARDIO
Like it or not, cardio will do amazing things to your gym gains. Cardio releases natural testosterone, dumping it into your blood stream during sustained endurance. Cardio is actually awesome. Its like a natural steroid. It of course it burns fat too. It pushes you mentally through physical pain barriers that you may not be used to. This has a positive impact on your gym performance because it reminds us the pain that is possible which we need to achieve in the gym to rip muscle.
Cycling
Body Pump
Running
Hiking
Most gyms have free classes and you should break out of your comfort zone and give it a shot. I am the only dude that attends the Body Pump class at my local YMCA 1-3x's per week and it whoops my ass! Totally worth it. Long hikes with elevation is great, and cycling is fun, motivating, and a great workout. I have always been a Mt Biker, but recently got into road cycling as well and love it. Highly recommend it! Running is great in the winter time when salt is on the roads and conditions aren't the best for other sports. Add in some hills to switch it up. Flat mentally kills me, but when I add in the up hill challenges, the down hill reliefs, and the occasional flats, its enough stimulation for my mind to keep me engaged!