The melody of I Don’t Know Why (I Just Do) by Frank Sinatra runs 197 notes across 25 bars, 2:19 long in Eb at 76 beats per minute. The tab sits almost entirely in the first two frets, one note at a time — no chords to barre and no strumming pattern to keep up with. A piano backing track plays the chords and bass underneath, so the line you are learning sounds like the record even at half speed.
Prefer to strum and sing it instead? I Don’t Know Why (I Just Do) chords and lyrics.