You would be immortal and all basic amenities essential for physical survival would be provided. You can have the age of your body according to your choosing and your mind won’t blow off by accomodating endless amount of memory.
You can choose anything you desire and that too at any instant which may or may not exist in real life, like an endless supply of something or a companion with the same immortality powers as yours, but you won’t be able to change it in the future and there would be no going back. Also you cannot alter your mind in any way that would enable to let you tolerate living for eternity or not get bored of things.
Ideally you would want to have everything just to be sure but by asking you the minimum requirements, it would making it more interesting to know what you think you could do without or what matters to you the most.
Would choose 45 as the age to stay. I would need an option to be able to die, in case the world I was on exploded or something, and some immortal companions. That’s the main requirements. I think in terms of getting bored, it would take a really long time if we could go all around this world and watch it changing, and eventually if it’s possible to get bored we would, it seems unavoidable.
In practice, I wouldn’t take this option since I already had kids. I think you have to choose one or the other, immortal beings can’t procreate, that’s the rules, it can only be one in, one out, not an increasing population and also it would be too sad to see my kids get old and die.