'Endless Cardio is all I need to lose weight and tone'
Cardio will cause you to lose weight at first but it will only get you so far. A, your body will reach a plateau as it isn't being challenged enough. B, you can't get toned from running on a treadmill. C, it can be really easy to not work so hard.
First of all 'tone' is what you have when you build muscle and this can't be done through cardio. you need to be working the muscles through contractions under tension and the only way to do this is through lifting weights.
Secondly focusing too heavily on weight loss can become a very obsessive habit and take over your life. You don't need to ruled by a number on a scale especially one that doesn't take into consideration your muscle mass, body fat etc. A person could look very slim but actually have a pretty high body fat aka skinny fat.
Go for how you look and feel. Take measurements and progress pictures to track your journey rather than obsessing over that scale !
Thirdly you need to make sure your diet is effective in order to get you get slimmer, and this doesn't mean drastically cutting calories ! Wholesome natural food choices in the form of carbs, protein and fats, plenty of water and allowing treats now and then.
I am not saying Cardio isn't a good form of training - it is and has it's place in a training plan. But it shouldn't be the be all and end all. If you are wanting to slim down focus on fat loss rather then weight loss. Combine weight training with HIIT sessions 2/3 times a week and 1-2 longer steady state sessions (LISS) a week.
Weight training is going to build your muscles and help create that 'tone' you are looking for. You will get an afterburn effect where you continue to burn calories after the session as well as ramping up that metabolism!
HIIT will build up your endurance, burn that body fat and get that heart rate going. I advise doing this at the end of a weight session or a longer one on its own.
Make your LISS fun for you - running outside, long hikes, fitness classes etc.
A combination of the above is going to help you reach that goal sooner than all the cardio :). Also a quick tip - make sure you focus on one clear goal first before you go for another. This way you are more driven to get there as well as creating a workout plan that is specific for that goal.
I hope this has helped you understand why the above quote is a myth and what will work better instead :)