Thanks for answering my query. It's a bit of a surprise for me that you consider calmness of mind, spiritual insight, better health and more creativity as side effects. I thought these are what most sadhak's look for when they start sadhana.
I never went 'looking' for anything. What is there to look for? As for mantras, I have one and one only. Occasionally, just for one particular reason, I say another one loud and clear in a temple. But the one in sadhana ... always the same thing ... over and over ... that's usually the prescription.