如何仅通过VBA在特定单元格内进行求和

In reference to the picture below, I would like to loop through a certain column (Column D in this case) until I hit a specific cell (Yellow cells in this case). In my final spreadsheet I have multiple yellow cells that I would like to target. Once I hit a yellow cell, I would like to start a simple summation of the values one cell to the left of the yellow (Column C). I would like to keep summing the values until I hit a blank cell, which would indicate the end of the set.In reference to the picture below, I would like