Mostly I love being physically embodied, I love seeing and feeling, eating, sex, lived being pregnant, I love having a physical body and consciousness.
What sucks to me is not necessarily physical decline - in general I've been able to handle what is thrown at me. I do hate time though. Hate the way we experience it in one direction. Hate the irreversible past that leads to the unavoidable future, it seems to just all be rolling out with no way to change it, every action came from some past action. Not just a big ship to turn, more like it will turn or it won't but we can't make anything happen that wasn't already going to happen. Our present the irreversible past of tomorrow's unavoidable future.
If you are ok with a fun for now thing and both of you are on the same page about it, no, it's not at all a waste of time. Aren't you still a teenager? Don't look for some forever thing yet, enjoy yourself!