If you don't want eternal life, then what do you want? What are your terminal goals/values? What are you ultimately aiming for? What is your existence reduced to?
My point is that there is no worthy alternative to eternal life.
At best, you'll just want to live forever under condition X.
This could be, for example, health or happiness.
But the truth is that maximizing lifespan involves not just health or happiness, but becoming techno-gods, conquerors of galaxies, beings of entirely new intellectual horizons.
In the short term, in theory, it may be necessary to sacrifice something, but eternity is worth it.
In practice, I think that the pursuit of eternity is a win-win. We will not lose anything, we will only gain. It is very unlikely that efforts to prolong life will lead to prolongation of an unhealthy period of life, most likely the opposite. And the willingness to be unhappy makes happy.
There is nothing that so clearly points the way for humanity and for each individual in particular as immortalism.