Try starting with what you're putting in your body
It might sound obvious, but if you're planning on making improvements to your health, the first focus has to be what you consume. Sugar, alcohol, caffeine all have an effect on your motivation. You have to be motivated and disciplined to start getting fitter. Once you cut those things out, you'll feel better and exercise more readily. Also, sugar, fast food, alcohol and caffeine all affect your mood and your metabolism, often for the worse.