I have been experiencing mild lightheadedness when i stand up for a few years and i believe its happening more frequently. im 36, in shape, eat healthy and havent had any blood pressure issues.

Lightheadedness: The most common cause of becoming lightheaded upon standing is a drop in blood pressure on going from sitting or lying down to standing. Measure your BP sitting and then up on standing. If the systolic BP drops more than 15-20 points this would be abnormal, could cause lightheadedness and is called postural hypotension. There is treatment for this. See your MD for evaluation and advice.