Yes, I always feel this way when I get a new very intense special interest. I feel like I'm "cheating on" my old SIs. I think the best way to handle it is to just try and shrug it off. As you mentioned, your primary special interests are inevitably going to be revived with a vengeance, so try not to sweat it. While it may feel like you're "betraying" your biggest SIs, and you may worry that your new passion means you don't love your old SIs anymore, you seem to be like how I am- you WILL eventually return to your old SIs and will never love them any less. So, just try and enjoy the thrill and the rush you only can get from a brand-new SI and not spoil it with worry.
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Helinger: Now, what do you see, John?
Nash: Recognition...
Helinger: Well, try seeing accomplishment!
Nash: Is there a difference?