While loops

I was wondering how you would make two while loops start together without their other conditions starting at the same time.(without the if not stmts starting.)
-------------
while a>b
do-this
-------------
if not-do this
-------------
while c>d
do-this
------------

Not completely sure about your question but think the attached is what you want. The key principle is that any ("reasonable" ) number of methods can be running at one time.