Lookup value based off previous record
I have used the invoice starter template and modified it to work with my gym in monitoring workouts. Essentially Products have become Exercises and Invoices have become Workouts. I've added a couple of fields to the Exercises (formally Products) 1RM and Previous 1RM. 1RM is a calculated value, I've got this working great but I'm trying to get Previous 1RM to show the calculated value from the last time the customer did the exercise.
It would be similar to pulling the Quantity for a Product on a New invoice from the previous time the Customer bought that product.
Thanks in advance.