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.
Heat the pan on the stove for about two minutes or until it reaches medium to high heat. Gently lay each tuna steak on the hot griddle pan. Let the fish sizzle and don't move it around in the pan. Cook for only 2 minutes on the first side for a rare steak, or 5 minutes for a medium.ne-inch thick tuna steaks can be perfectly cooked in about 10 minutes. Much like a good sirloin or quality beef steak, tuna suits grilling or shallow frying in very hot oil. Use a marinade for extra moisture and to add flavor to the fish.