Squats, box step-ups, step-downs, split squats, lunges, glute bridges, and Romanian deadlifts are the best strength exercises for beginner hikers. Choose 1-2 "quad dominant" exercises like squads and lunges and 1-2 "hip dominant" exercises like bridges and deadlifts and do 3-4 sets of each exercise for 8-12 repetitions per set. Two strength workouts per week should be enough!