Dear m. canales90,,
I am sorry to disappoint you, but fat injection to the the butt disappear completely or almost completely after one year. That has nothing to do do with working out. When you shove into the buttock a large amount of fat that is lacking circulation, it will not survive. It takes about a year for the fat to get absorbed and the scars under the skin to mature and go down in volume. Buttock augmentation with silicone implants feels and looks natural. Most importantly, they do not disappear. Consult with board certified plastic surgeon who is experience in that procedure. Check the before and after and make sure that you like the result. The implants come in few shapes and consistencies and can be placed in different anatomical locations.
Best of luck,