i feel like you've shifted the goalposts, here. previously, you said you didn't want to live forever, now you're just saying you can't live forever.
also, we absolutely do have genetic engineering. it's been a thing since the 70s. the covid-19 vaccine, for instance, was a feat of genetic engineering. furthermore, techniques such as gene therapy can indeed modify the genetic information of adults.
P.S. i assumed you meant physically, rather than psychically, but if you did mean the latter, then i have no idea what you're talking about.
do you want your kid to die someday as well? what if your quality of life didn't have to become bad? immortalists such as myself (that is, people who don't want people to have to die, and support scientific efforts to make that a reality) don't want people to just, like, persist in a state of unending geriatric decrepitude, we want folks to be able to live as long and healthy lives as possible.