Is this enough?!

Is this enough?

i am trying to lose weight and i am wondering if the exercise im doing so far is enough. i am big but not fat. add like a 1/4 of big to medium and thats me. i am 13 years old. what i am doing right now is:

i turn off the AC in my room and it's around 40*C outside. i wait for the temperature to go up then i do 150 sit-ups. then i sit half upright and hold my position there for around 70 seconds. i want to have a mild " 4 pack" abs. check out this picture and you will get an idea what i want. it's a pic of zac efron http://data-allocine.blogomaniac.fr/mdat...

thanks so much for people who answer properly and there is 10 points up for grabs!

6 days ago
i do the exercise everyday

If you don't lose fat and carry most of it in your mid section you can do a thousand sit ups per day and not see your ab muscles. Everybody has "six pack:" abs. However for most people they are covered up by fat. Building muscle all over is going to help you lose fat. You are doing plenty of situps to tone and build your ab muscles. The "70 second hold" is doing very little for you. And the AC thing is just making you less comfortable and is slightly counter-productive to achieving your goal. You burn more calories when you are cold. Also get out and walk or jog for 30 minutes.

I see plenty of overweight people doing 100s of sit-ups and working on ab machines at the gym. I'm sure they have toned and large ab muscles but nobody can see them for the fat covering them up. You don't see fat on people with "six packs".