Using just one string anywhere on the fretboard:
Ascend 4 half-steps (a half step is one fret higher on the neck of the guitar), using the index, middle, ring, and pinky finger.
Thus, if one is at the 5th fret, play the 5th fret note with the index finger, the 6th fret note with the middle finger, the 7th fret note with the ring finger, and the 8th fret note with the pinky finger.
Repeat this many times, but if you feel any pain, please immediately stop, and rest. Maybe try it again the next day.
Play this pattern with alternating pick strokes and/or down strokes.