You have as many different aging problems to solve as you do types of cells in your body: hundreds. Stop one cell type from aging and all other types go right on with their pre-programmed aging process. There is no magic signal that tells all cell types to simultaneously stop aging - rather, it is designed into the DNA of each separate type of cell. Thus, a massive gene modifying project becomes necessary. If you do not eat genetically modified foods, why would you want to live in a genetically modified body?
Another wrench in the gears: have moles on your skin? Probably many of them - some that are not pigmented, and some are beneath the outer layer of skin. Moles are pre-cancerous skin cells. Extend life long enough and they will all become melanomas (skin cancer). Then, you have something else to cure in addition to those hundreds of separate aging processes.
Oh, the aging process in the DNA of each different cell type is also perfectly synchronized with the others. How are you going to accomplish that, given the hundreds of cell types that will need individual modification?
Modify each type of cell and you have another problem: your immune system. The T-cells that are trained as infection and mutation fighters by your thymus will now begin to attack your new, non-aging body cells. Those modified cells will contain different proteins on their surfaces - proteins which are recognized as a enemy by your immune system. Your body will be at war with itself, as in an auto-immune disorder, or graft-versus-host disease with transplant patients.
You will, at some point, have to stop human reproduction, if each person is living much longer. How do you do that world-wide?
Practically speaking, we know that the earth will come to its end. Who knows when, but the sun has a set life expectancy. Let’s fast forward: say that you are 240 years old and it is the earth’s last day. You are glad to be there to witness it, but who will you tell about it? If you cannot fathom anything beyond this earth, why live at all?
This may be wonderful to daydream about, but who is going to genetically modify the first geneticist to live long enough to see this idea through?
What if there is another life, where nothing bad exists? A place where you receive your perfected body back, and there is no death; no aging because there is no time. Oh, but you must trust and have faith to experience that…