Don’t sweat it
Definition 1 of 1
Pro Tip 1/3Colloquial Usage
'Don't sweat it' is informal and best used in casual conversations, not formal settings. 
Missed a party? Don't sweat it, there'll be others.
Pro Tip 2/3Reassuring Tone
The phrase often carries a reassuring tone, suggesting that the issue is not serious. 
You spilled your coffee? Don't sweat it; it's an easy clean-up.
Pro Tip 3/3Common Responses
It's often used as a response to apologies or mistakes, to reduce the other person's worry. 
You forgot my birthday? Don't sweat it, it happens.