How can we learn to interpret the meaning of physical issues or illness?

Oh, so much to say. But first, this.
The following article does not contain New-Age Guilt.
Do your thought-patterns, emotions, and beliefs have an impact on the physical body? Yes. Yes they do. 
Candace Pert, Ph.D., wrote in her book, Molecules of Emotion, about how our bodies and minds function together as parts of an interconnected system. Fascinating stuff, that.
Louise Hay’s book, You Can Heal Your Life, lists probable thought-patterns related to physical ailments and suggests new though-patterns for each. For instance, she lists hip issues as a fear of moving forward. 
You can use this as a starting point, perhaps by diving into some self-discovery through journaling or working with a therapist or coach.
And… ever the fan of the paradox…sometimes stuff happens and we cannot access the why, because of our limited view of reality in this dimension. It may be due to group thought-patterns, or beliefs inherited from family, or, or, or. 
But we can choose how we perceive our experiences, what thoughts and feelings we decide to entertain in every moment. We can engage our internal world with love, compassion, and acceptance as we decode the thought-patterns our body is urging us to shift within ourselves.