Do no regret Tamas, but when sattva comes into play, hold on to it and make the best of it. —-Maharishi Ramana.
Comments; These are Vadantic vocabulary when the mind is cool and happy that stage is called sattva and when we feels laziness or sleepy that stage is called tamasa .When we are in tamasa we cannot succeed in meditation we should not regret this time and let it go but when sattva ( calm and happy ) stage comes it is better for meditation.
As I did my whole life after some exercise like walking or yoga it will be a good time for meditation. Music and dance also very good before observation. I mostly do dance with music for 45 minutes and then sit in meditation for a long time. It gives me the best result from the experience of bliss.