Sometimes when you generate an nsec instead of creating one in a client, the clients will not let you follow anyone, because they can't find your contact list, when you create an nsec from a client they generate a contact list where you follow yourself. 

If you're somewhat of a dev you can fix this, by generating a kind 3 event with your own pubkey. Or you can trial and error different clients until one let's you follow someone, try to open your own profile and see if you can follow yourself. 

If you need an easier option, just ditch this key and and create a new one from inside a client. 

 Hmm okay! I’m not a programmer unfortunately—I’ve already been engaging on this key for a while now so I’d prefer not to start over. I did my profile through Iris. What do you mean with clients in this context? Apps? 

 Yes like damus, iris, nostur, primal