In everyday emails, it's not unusual to see, "Please call John or myself if you have any questions." Only you can make a call to yourself, and if you leave John out of the sentence, you'd say, "Please call me if you have any questions." The correct use is "Please call John or me if you have any questions."
A stationary bike stays in one place while you ride — let the "ar" remind you of “at rest.”
You'll find office supplies at the stationery store — let the "e" remind you of
the e's in "letter" and "envelope."
“Hopefully, the sun will shine on our picnic,” actually means that the sun will be hopeful when it shines on the picnic. "Hopefully" is an adverb, which modifies a verb. "Hopefully" should not be used as a substitute for "I hope." Say, “I hope the sun will shine on our picnic.”