How to easily limit the number of rows in your Excel Power Pivot model

I am currently working with an Excel Power Pivot model with about 20+ million rows in the model, and as there are a lot of Excel reports in the model and some of the calculated fields are pretty complex it takes some time when I move calculated fields, format them or change them.

The model retrieves data from a SQL database so the table queries are either Stored Procedures or handwritten SQL statements.