Count Function To Count From A Set Point On Recurring Basis

I want to count from each cell that doesn't contain "0". So if cell C2=100, I want to be able to count the number g1*2 from that cell and return a value. But then I want to start another count from c5 to the number of g1*2 and then another count from c8 etc basically any cell that contains a value other than "0", I want to start a count from.

The point of this is that the half life will expire after that count, so I want to be able to add the drug levels on an ongoing basis until the count of the half life has been reached. But there will be further dosing along the way before this half life is reached and these values need to be added to the existing value until the half life expires.