Do not replace the common phrase try to with the often nonsensical colloquialism try and when the intention is to demonstrate an attempt made. Prefer We must try to relax to We must try and relax. The former shows an endeavor to relax, the latter implies both an attempt to be made (at what is left unsaid) and a call to relax.
Although Bryan A. Garner suggests that try and is a standard idiom in British English, common use begs to differ—the correct phrase appears over six times as often in both American and British English.