Do not regret tamasa, but when sattvica comes into play ,hold on to it and make the best of it. —– Maharishi Ramana
Tamasa meaning that state of mind when we feel lazy, sleepy, sometime you know it is very hard to work or read, so at this time we are not able to do meditation so let it go and when the mind comes into the state of peace, happiness that time start to do meditation. Because our mind changes according to our vassanas. Our mind has the effect of our karmas in this life and in previous lives.