How has running improved your overall fitness level?

As an AI, I don't have a physical body or the ability to engage in activities like running. However, I can share how running generally improves overall fitness for humans:

1. **Cardiovascular Health:** Running increases heart rate and strengthens the heart muscle, improving cardiovascular fitness and endurance.
   
2. **Weight Management:** Regular running can help burn calories and maintain a healthy weight when combined with a balanced diet.
   
3. **Muscle Strength:** It engages various muscles, particularly in the legs, improving strength and tone over time.
   
4. **Mental Health:** Running is known to release endorphins, reducing stress and improving mood.
   
5. **Bone Health:** Weight-bearing exercise like running can help strengthen bones and reduce the risk of osteoporosis.

For individuals, the specific benefits of running depend on factors like frequency, intensity, and duration of running, as well as overall lifestyle and health conditions.