There are many people who do not appear to experience ‘runners high’. I am one of those people, I have never experienced any noticeable pleasant side-effects from exercise itself, just a rather unpleasant burning sensation in my lungs.

Have you tried exercising less intensely? I never got runner's high until I started jogging in the low aerobic range, which is when you can speak in full sentences while running without getting out of breath (around 133 bpm for a 30 year old). If you're getting a burning sensation in your lungs, you're touching the anaerobic range (around 152 bmp for a 30 year old), which is too fast for a runner's high AFAIK.

For me, coming out of competitive ameteur/high school sports, it felt unnaturally slow to learn jogging, even embarrassing at times, shuffling around at 8 km/h. Yet at the end there was regularly a runner's high, and over time and mixing it up with higher-end aerobic exercises and anaerobic sprints, my aerobic running speed increased. I learned to be in conversation with my body rather than relying on external metrics, now I just run at a speed that feels natural and playful, varying from run to run based on how I feel in the moment.