Try transitioning your emotion midway through your copy, at a natural point in the voice script. If you start with a joyful/happy emotion, midway through, transition into another emotion...possibly "contemplative" or "mischievous".
Or try transitioning with loudness/softness of your voice. Or with a brief pause or beat at certain points in the script.
You most likely already do this from time to time. But it's great to remember to do it when you're stuck!
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