Don't allow the mind to keep thinking the the way it wants to. When we let our minds to wonder, it can become very much our reality. It applies to everything (even our lives - our whole life becomes a day-dream). Mind goes far. It takes us along with it.
How to Stop Proliferation?
Meditation the best antidote for Papañca (Proliferation).
Step 1: Remain heedful, ardent, & resolute.
Step 2: Whenever thoughts arise, note which kind of thoughts lead to trouble and which thoughts don't*.
Step 3: Seeing thus, simply abandon, dispel, wipe-out the troublesome thoughts.
1) thoughts imbued with Greed/Hate/Delusion
== lead to ==> drawbacks, degradation, defilement, my and/or others affliction
2) thoughts imbued with non-Greed/non-Hate/non-Delusion
== lead to ==> rewards related to renunciation & promoting cleansing, discernment., my and/or others happiness/benefit