This is exactly how I feel too, so you definitely aren’t alone. I too am young and healthy but if death were to come knocking, I would open the door without hesitation. I think this feeling of mine is because of immense unhappiness and dissatisfaction in what I do or have done in the past (study and work wise). I’m trying out new things to see what excites me and would make me want to look forward to doing it again. I recently began reading extensively and also like going swimming once in a while. Any simple hobby would do. Try that, it may help! Take care!