Why would you worry about immortality?
The average adult person will live maybe up to their 80th year.
There's a chance that technological progress might expand that live span.
If you are young enough, there's a chance that you might benefit from this.
There is a tiny chance that your life span is extended so much that during that lengthened life span there is more technological progress, which lengthens your life span further and during that further lengthened life span there is more progress again and so on. In total, your life span may be very, very long.
There are a few consequences.
The chance that you die by accident or as a crime victim grows. Every year about 4,000 people die in traffic accidents in the UK. That means your chances of living 100,000 years without dying in a traffic accident first are very, very slim. Unless you change your life to systematically avoid any situation that has the tiniest chance of leading to an accident, and maybe that would make your life quite boring.
You will have plenty of time thinking about the answer to your question, and since you will be older and wiser, you are likely to find a better answer than any we could give.
You would also have a very very long time to think about everything. And there is a chance that after some time, you'll just have enough of it all. You are worrying about what happens at the end of the universe. You should worry that immortality might become first boring, then annoying, then unendurable, and the prospect of dying at the end of the universe might be the only hope that keeps you alive.