There are some good reasons to take a loan from your 401(k) -- for instance, when you have absolutely no other options and the repo men are on their way to your house.
Other reasons may just be elaborate rationalizations, says Casserly.
"People justify to themselves why they're taking the loan by saying, 'I'm paying myself back.' You're not making back all the interest. There are administrative costs and fees that come out of the interest," she says.
How to recover: Recovering from a 401(k) loan takes time. Pay back your loan and save for the next big purchase or fund an emergency savings account rather than falling back on money that should be untouchable.
"Savings accounts are too accessible for the average American today. My suggestion and solution is create an account that is not accessible at your local bank or ATM and then save systematically on a monthly basis," Casserly says.
"Very few people have three to six months' of living expenses in a savings account because they say, 'Oh, but I had to go on vacation,'" she says.
Save up for a rainy day to avoid raiding your retirement account.