This is a very interesting question with many different ways to take it.
Does living forever on earth still mean that there's a God? If there is, then why hasn't Jesus returned to stop this "forever" time? If there isn't, then how am I able to exist in the first place with the capacity to live forever and how am I being sustained? Am I a god? If the god that is there isn't the God that I worhsip, what kind of god is he and am I meant to be spending my forever time worshipping him?
Does living forever on earth mean living forever on the new earth? In which case, I can't even imagine what I'd do because I'm not there yet. But I hope I'll spend the days with many friend having very good conversations, eating teacake and scones, drinking lots of tea and not suffering any bad after-effects like weight gain and shaking from too much caffine.
Assuming that there's no God and I'm going to live forever, what's the point of doing anything at all!? It would only get boring and I'd have no one to answer to. I'd just have to make sure I don't get a life sentence in prison because that would suck tremendously. I mean, suppose I try and find my one true love. Great! But then he dies 60 years later. Would I devote myself to social justice instead? Campaigning to make the world that I'm spending forever in a better place? Would I pursue wisdom and work for many uni degrees and doctorates, reading books and consuming media?
Bringing up another question, what kind of state would I be in when living forever? Would I stay as I am: a 22 year old women with reasonable fitness and health? OR would I still age? Would I be living forever as a vegetable in an aged care home?
Thank God that I am going to be living forever in Heaven with Him. That I am going to a place where I'll be in perfect relationship with everyone around me. Where nothing bad happens, where everything is good and pleasing and I will be satisfied. Thank God that I will not be living forever on this earth, that is full of so much pain, suffering, dying. Everything that is good in this world will remain in the next and be better, fuller, more whole. But everything bad will pass away.