I only have a limited number at any one time. Some are long standing - the most enduring being my work. I am fortunate to be actually paid for spending 40 hours or so each week engrossed in something that fascinates me so much.
As regards other interests that have come and gone - for me they usually start with a repetitive thought process, often when I between consciousness and sleep, I then ruminate on it more until I am compelled to act on it. Some interests ebb away to be replaced by others only to return years later. Some never come back. I sometmes go for long periods where I only have my main 'work' one.
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Diagnosed: ASD, hEDS, MCAS, ARFID
Retired specialist neurodevelopmental clinician
Member of Autistic & LGBTQ+ communities in South West UK
Trustee at Cornwall Pride charity & Coordinator at Kernow Neurodivergent Artists network