Supernova blasts leave behind a rotating core that continues to spin faster as it collapses.
Recurrent novae begin to flash faster and faster as they consume more and more energy and material from their companion stars.
Gravity from a nearby black hole pulls the neutron star into an increasingly tight spiral.
Gas spiraling in from a nearby companion transfers angular momentum to the pulsar, increasing the rate of its rotation.
Jets of energy emerging from the sides of the rotating neutron star cause it to spin faster and faster.