Focus on one thing at a time in order to really get it ingrained as a 'good habit'. For example, for one month, focus on adding healthier foods to your diet (and dropping some of the less healthy ones). After that month, it’ll be ingrained. The next month, add walking or jogging, and only focus on that. One goal at a time, one month at a time, and you’ll get healthy.
Try to do something every single day that will help you get healthier!