In my Alteryx workflow, i'd really like to have a data input, followed by a field selection, and then set up some variables which can then be easily assigned fields from the data input.. currently my workflow is like this...

Data Input, data cleanse, field selection, then the formula tool to add create the variable to use downstream.
Does anyone have any suggestions please on how can I then assign input values to those variables, but using a drop down list, rather than having to manually type them in under each variable name within the formula tool? is there a way I can achieve that and help make the user experience better?
Thank you
Alex