just for kicks

Just for kicks, here's one more chord progression to practice uses the Am chord in a more familiar context. Four beats, or four strums to the measure. On a C chord, begin your strum on the fifth string. On an F, begin your strum on the fourth string. On G, begin from the sixth string.

C    Am    F    G

C    Am    F    G

If this sounds a little familiar to you, the above is one of the most common chord progressions used in the history of popular music. See if you can't find some songs that use these chords, either in the order given, or in a variation.

Maybe you noticed that C and Am have two fingers in common. Changing from C to Am involves little more than moving your ring finger from the fifth string, third fret, where C needs it to be, to the third string, second fret, where Am needs it to be. 

Am and F have one finger in common, the index finger at the second string, first fret. Leave it there as you wiggle your ring and middle fingers into position. Then try to flatten your index finger to a half-barre to cover both the first and second strings at the first fret. That's a lot to juggle in one measure, but keep strumming.

To get to G from the F position, first get your ring finger to the sixth string, same fret. Your middle finger will follow as you let go of the half-barre. Then add your pinky to the first string, third fret. 

To play this progression well, a lot of fingers have to fly around the frets. If it seems difficult, that's because it is. But I'll bet it's not as difficult as when you first tried to change from D to A7 and back. Maybe not, but this is what making progress feels like. The day you can handle these changes is the day you've gained good dexterity in your fretting hand.