Decline is unavoidable, just a question of when and how quickly. Isn't it better to be at peace with it, as in broader sense also with aging in general?

There are sports where pleasure can be easily experienced, coupled with other intense positive emotions. Rock climbing does it for me (it works with something in our monkey brain and it works very well), some more adrenaline sports get you there too.

But its perfectly fine to not even seek pleasure, that's one way to sustain efforts for long since health benefits especially for white collar workers are massive.