Phenomenon is a 1996 film starring John Travolta as an amiable, small-town everyman who is inexplicably transformed into a genius with telekinetic powers.
Not lightning, but on his way home from a bar,

..... he notices a ball of shining bright white lights in the sky. It grows closer and appears to hit him, making a loud sound and knocking him down. Nobody else saw the lights or heard the sound. George begins to exhibit remarkable levels of intelligence. He easily absorbs vast amounts of information, formulates new, revolutionary ideas, and develops telekinesis. Not needing sleep, he spends each night reading multiple books.

George tries to use his new intelligence for the good of his community. He develops a powerful fertilizer, improves solar panel designs, and predicts an earthquake without any equipment.

Ooh, I read the synopsis - I had totally forgotten the ending. Ok, no spoiler from me!

According to screenwriter Gerald Di Pego, the philosophy of Zen influenced the conception of George’s tapping of his mind’s potential. The movie also draws influence from Scientology, which actor John Travolta is a member of, drawing from L. Ron Hubbard's book Dianetics.

Just when I was ready to go out and get struck by lightning in hopes of becoming a math whiz!