You do not need a free afternoon to pick up your acoustic. Start with a small session that has a beginning, a middle and something enjoyable at the end. This fifteen-minute routine is a starting point to adapt, not a test to pass.
First, make room for the music.
Put your phone aside, choose a comfortable place to sit and bring your guitar into tune. Decide on one thing you want to explore today: a smoother chord change, a steadier strum or the opening of a favourite song. Keep that intention small enough to remember while you play.
Five minutes of rhythm.
Choose two familiar chords and alternate between them slowly. Count four steady beats on each chord. If a change interrupts the rhythm, make the pattern simpler rather than trying to rush your fingers. You can even practise the right-hand rhythm with the strings lightly muted before bringing the chord shapes back.
Five minutes of one small challenge.
Take the section that keeps catching you out and make it shorter. Work on the movement between two shapes, or just the last beat before the next chord. Listen to whether each note rings clearly. Leave space between attempts so you can decide what to change instead of repeating the same movement automatically.
Five minutes of something you love.
Finish by playing music, even if it is a simplified version. Use the easier chord shapes, leave out a difficult fill or sing the melody while you strum. The point of the exercise is to connect the small skill you practised with a sound you enjoy making.
Before you put the guitar away, write one sentence about the next session. “Keep the rhythm going into the chorus” gives tomorrow a clear starting point. Keep the routine flexible: on a busy day, one focused section is still something worth playing.