What other people think about you is none of your business; what you think about yourself is most definitely your business.
As adults, we are quite capable of setting the bar for our own moral, spiritual and physical standards, and I firmly believe that once you are comfortable with the standards you set for yourself, then that's between you and the Almighty.
Thinking positive
In modern times, self-esteem in women and men seems dependent on how they think they look. How you see yourself is vital, because this will affect your behaviour. I remember in my late teens "tracking" this beautiful girl, who seemed intent on putting me down. Her last blistering remark to me was: "I only go out with tall, dark and handsome men!" To which I replied: "You are being a bit hard on me, two out of three is not bad and I am working on my tan."I got a smile and the date. You have got to think positive. Having said that, it is challenging for you to think positive if your mirror reflects a flabby, out-of-shape body.
Improving body image
It's not hard to get in shape, once you understand basic fitness principles. In your quest for a great body, you have got to know the role that weight training and cardio will play in your fitness programme. Contrary to popular belief, you, in fact, burn more fat with weight training than you do with "steady state" cardio (running, biking etc). If you look at the bigger picture, it is the after burn or post workout effect from weight training that turns your body into a fat-burning furnace. After an intense weight-training workout, your metabolism stays raised for as much as 38 hours and, as you eventually build more muscle, the effect on your metabolism becomes permanent.
However, this should not be taken out of context and interpreted that cardio is useless; it is important to continue cardio training as part of your fitness programme because it is still the most proven form of exercise for strengthening your heart. You must strike a nice balance between cardio sessions and weight-training sessions. If you wish to improve the fat-burning effect of cardio, you must consider performing HIIT (High Intensity Interval Training) at least twice per week. Performing cardio in this manner causes you to build up an "oxygen debt" to the tissues, which has to be paid back even when you are in post workout mode–thereby keeping your metabolism raised. Enhance your body image and it will do wonders for increasing self-esteem. Keep training.