אֲנִי מְתָאֵר לְעַצְמִי
In English, when we make an assumption and create a potential scenario, we might say "I imagine," as in:
I imagine the neighbors think I'm crazy.
In Hebrew, this form of I imagine is אֲנִי מְתָאֵר לְעַצְמִי listen and repeat - literally, I describe to myself: When we imagine a scenario, we describe it to ourselves, sometimes in great, obsessive detail.
Thus the above sentence would sound, in Hebrew, like:
אֲנִי מְתָאֵר לְעַצְמִי שֶׁהַשְּׁכֵנִים חוֹשְׁבִים שֶׁאֲנִי מְשֻׁגָּע.
That's when the speaker is a male. If the speaker is a female, the expression is אֲנִי מְתָאֶרֶת לְעַצְמִי listen and repeat.
Now, all this applies when assuming that a scenario is true. The generic verb for to imagine is the active-intensive לְדַמְיֵן listen and repeat, as in:
הִיא מְדַמְיֶנֶת עוֹלָם טוׁב יוׁתֵר.
She imagines a better world.