1 Add time each week to work your way up to 30 to 45 minutes of continuous exercise. 2  As you get stronger, try interval training once a week to help boost endurance and burn more calories.  Work your way up to 5 to 6 days of cardio and try to vary what you do and how hard you work.
To achieve a sear on the outside and keep it rare inside, place the tuna on the skillet or grill and let it sear for two minutes on the first side. Flip the tuna and let it cook for another two minutes, then remove it from the heat. Watch the tuna as it cooks to make sure you don't overcook it.
1 Mix Well. 2  Pour over Tuna Steaks and marinade 20 minutes, turning occasionally. 3  Make sure grill is hot â place steaks in hottest section and Sear steaks 1 to 2 minutes per side to seal in the juices.4  Finish cooking just slightly away from the hottest area â 8 to 10 minutes per inch of thickness. Pour over Tuna Steaks and marinade 20 minutes, turning occasionally. 2  Make sure grill is hot â place steaks in hottest section and Sear steaks 1 to 2 minutes per side to seal in the juices.