lasting for a short period of time
ephemeral - temporary
If you describe something as being ‘ephemeral’, you mean that by its nature it typically only stays or lasts for a short time. Take the concept of fame as an example. Fame is ephemeral because it is fragile and fleeting. It is something that can and often does vanish as quickly as it arrived.
Success in the entertainment industry is usually ephemeral. Only a select few manage to stay at the top for any length of time.
That flower is only ephemerally green. It turns a dark brown after a few days.
I did once consider a career in Law, but my interest in it was only ephemeral.