before it’s too late

Я вас люблю, к чему лукавить?  Но я другому отдана, — И буду век ему верна.

-«Евгений Онегин»  Пушкин

Before making any decision, think.   Let the thought of anything else slowly escape your brain and embrace every consequence that decision may leave you with.  And don’t ever look back—because if you do, know that choice may not still be there for you.  And know it may have drifted away into the mind of someone else—someone else who will make the right decision and everything else will be history.