Mental time travel

Mental time travel is a method in which a person can time travel by actively switching from the mental state of their current self to that of their past or future self -- sometimes done voluntarily, and sometimes involuntarily. One notable use of this form of time travel is in the Star Trek: The Next Generation episode "All Good Things", where Captain Jean-Luc Picard mentally shifts among three different versions of himself in three different time periods.

Empath: The Luckiest Smurf stories
In the EMPATH: The Luckiest Smurf story "Days Of Future Smurfed", Empath in the present time, while possessing memories of a thousand years worth of future history, finds himself involuntarily shifting between his present self and his future self at different points in his future, mostly when Empath is experiencing a tragedy, such as the deaths of Papa Smurf, Smurfette, and Brainy.