In a sense you could yes. But if you cant do 45 mins straight why not try to slow down your pace of the exercises your doing. The key thing in losing weight is getting your heart to the fat burning zone and keeping it there. If you want to train cardio to try and lose weight and burn fat i would suggest doing INTERVAL training. Its fairly hard at first but in the end its only 16-20 mins of working out. Youll also get the best results because it gets your heart to the fat burning bpm and keeps it there faster. Runs, walk, stairs, or bike any cardio will do. -Start off with a 2 min warm up, slow pace trying to stetch and warm up all your muscles. -Then 2 mins straight go as hard as you can. -Then rest for 1 minute -Then 2 mins straight as hard as you can. -Then rest for 1 minute If you do the 2 min on 1 min off 5 times(so doing 2 mins at your fastest pace 5 times) with the 1 minute of rest thats 15 minutes of working out, plus the 2 min warm up. Just make sure to not push yourself to hard and only go as fast as you can. Your going to be tired and its going to be hard. But you have to push through that if you want results. Also dont expect results in 2 weeks... if you do this training 4-5days a week youll see real results by around 6-7 weeks. Thats the same with any workout routine your doing.