Solo training works for self-motivated people. For most, training with a friend, partner, or family member improves consistency, makes harder sessions easier, and creates positive habits that ripple beyond your own fitness.
What works
Walking partner for daily steps. Gym buddy for weekly strength sessions. Workout class with friend. Family hike at weekends. The social aspect supports the habit when motivation alone fails.
Find at least one training partner for at least one weekly session. Consistency benefit alone usually justifies it; the relationship benefit is bonus.