Knowing and understanding your characteristic according to YinYang theory can support you in finding balance.
Yin people tend to be more introverted, relaxed, embrace a sense of creative easily and may be more persistent.
Yang people are more action takers, ambitious, extrovert and get easily excited.
Yang people are easily angered, prone to headaches, insomnia, find it difficult to sit still for long periods of time and may be prone to addiction.
Yin personalities are prone to signs of excess such as oversleeping, overeating, weight gain and over thinking.
Based on activity preferences Yin people may be attracted to yoga, meditation, golf, fishing and other slower activities while Yang people may be runners, attracted to more aerobics or cardio based sports or adventure seekers.
Yin personalities prefer cool, sweet foods while Yang personalities might prefer hot, spicy and savoury foods.
It stands to reason that nothing is absolute with regards to YinYang theory. In fact understanding YinYang theory does require a deviation from a Western way of thinking. An oriental perspective requires seeing that both Yin and Yang are intertwined and that there is an endless flow between the two. One may transform into the other at various times during our lives. This can occur daily or we may idle in one energy for longer. The seasons may even affect how you interact with each.
To understand which is more dominate for you I suggest sitting in reflection on whether you are currently fighting or blending with your current state of feeling. What irritates you? Cold weather or Hot weather? Do you normally prefer cooling food or spicy food? Does your body respond to exercise? Or can you maintain your weight even while practicing slower less cardio activities? You will find that your body seeks balance.
If you have a sluggish metabolism your body will probably respond to exercise although you still have to work at weight loss if you are predominantly yin. An active metabolism is probably a more Yang based characteristic.
This is a very basic thought process regarding YinYang theory however might help you determine your dominating energy.