I used to practice meditation but have largely replaced it with Iyengar Yoga. I generally felt very good immediately after a session and I think it helped me in my productivity as well. However, I'm not so sure it helped me when I had to deal with high stress situations. The big problem that I have is when something becomes greater than just a hobby. For instance, when I did yoga for purely health reasons, I felt happier and better. But, when I started doing it with the thought of becoming as good as BKS Iyengar, yoga itself contributed to the stress.