Self-care time. Couples may spend time on themselves when apart. Long-distance couples tend to be more independent and self-sufficient.
You maximize time together. Long-distance couples spend time together more meaningfully. Knowing your time together is limited makes you more inclined to do interesting things and spend quality time together.
You realize your relationship isn't convenient. You know long-distance relationships aren't convenient! Long-distance relationships are only for strong couples.
You understand the connection better. Long-distance relationships make you look at the broader picture. Should you improve anything? Are there problematic behaviors? Distance helps you see the relationship objectively.
Together, you value each other. Long-distance couples rarely take each other for granted. It's easy to overlook someone's greatness when you see them every day. Long-distance couples are more appreciative.