First we need to know if there's any specific pain in any place, or its just a general ache due to disuse. Also, what is your age? Have you ever exercised before? What is your height/ weight/ body mass index? Are you a sedentary couch potato, or do you move about somewhat at least?
That said, I am assuming that your ache is just a non-specific symptom of a sedentary habit. In that case any structured Exercise program will help. Pilates are good, but remember, the key word here is 'structured'. It is best that you join a Pilates class which will provide you with graded exercise that keeps you motivated to continue.
Aerobics and Yoga are some other forms of Exercise, but then again, the important word is 'structured'; it has to be a long-term activity that exercises all parts of your body, otherwise there might be imbalance.
If you are a teen, then I will also recommend that you look at strength training, again under a trained fitness trainer, and with the correct workout for all body parts; especially legs, hips, etc. that one is laziest about!
I am in my 20s, and I am working in the office. So, mostly, I am sedentary.
I think I have som problem in my posture. Based on what you said, I think I should learn more about pilates.
By doing so, I think my body aches will go away. I also hope you become healthier.
Thank you very much for replying. I really appreciate!