Most running form issues stem from the hip. Strong hips especially the hip abductors play an important role in achieving optimal gait mechanics. There aren’t many workouts that are as simple and effective as Side-Lying Hip Abduction to improve Gluteus Medius strength.
Start with 10 repetitions each on both sides, for 3 sets. You can increase the repetitions, and also use a resistance band around the ankles to add difficulty. It is recommended that side-lying hip abduction is incorporated as part of your mobility & activation routine or as part of strength training.