Meditation, yoga, runner's high, are all the same relaxation response you are describing as your desired end effect. I taught progressive muscle relaxation (PMR) and using that with visualization anyone can get there. And yes it is all the relaxation response. I find progressive muscle relaxation to work for everybody when I guided them through the first session in a darkened room with them on the couch with loosened clothing and shoes removed.
Here is a set of search results with many free online guided PMR sessions and starter lessons:
progressive muscle relaxation - Bing Videos
If you spend a few hours reading and listening to several of the videos you should have it down pat in an afternoon. I also used it for training competitive shooters as once mastered you can get into the relaxation response for total focus, truly getting in the zone. I could get there in a few breaths. So to avoid the misunderstandings of mystical or spiritual trappings it is easier for me to teach PMR and in the first session prove that the mind muscle relationship is two way. That indeed when the mind is stressed, the muscles tense up. However it is just as consistent that when you relax your muscles, the mind follows. This is fact and requires only one to do, and one to teach only at first. The spiritual and mystical feelings are still there if you choose to frame the relaxation response in those schemas. The rewards are the same using any schema as the relaxation response is invoked with all of them. Getting there can be through repetitious athletics, focus, repetitious breathing or chanting, but PMR is a fast way to get there in a day. It is not a journey for me, it is a workout, and can even be done at a desk once learned for a feeling of getting a few hours rest in just a few minutes.