endorphins

Back in the day we would frolic like dolphins:
Tireless, fearless, careless, strong.
Now we are older and lacking endorphins,
Stuck in a world with the logic all wrong.
Raging insomnia, memory glitches,
Moodiness, dizziness, stiffness in joints,
Permanent aches, uncontrollable twitches…
It’s an impossible task: to rejoice. 
Enter endorphins: it’s easy to find them,
Worth all the effort, a lot to be gained. 
Go to a place specializing in vitam…
Supplem… Hang on, what’s endorphins again?
Someone has told me a market would have ‘em.
Tropical fruit with a yellow peel.
One little morsel and bang - you’re in heaven…
Poisonous? No, just the way you will feel.
Back to endorphins (the thing I’m describing):
Longish, two ends with a bit of a kink…
Green at the start, but you wait and they ripen.
Something related to slipping, I think…
Slipping? My bones are incredibly brittle:
One little tumble is all that it takes.
Ditch the endorphins, give up on the riddle:
Fruit can be lethal. I’ll stick to my cakes.
Totally obvious - sweetness can numb us:
One little crumb – and our worries are gone.
Cakes can prevent us from going bananas…
Strangely familiar expression… hang on…