"In 2014, we focused a lot on lending and recalibrating our lending offerings to make sure that they were current and meeting the needs of the membership," Mendez said.

One part of that effort has been particularly effective at attracting assets: The timely repayment incentives program, or TRIP, Mendez said. That program attracted borrowers with blemished credit by knocking 50 basis points off their auto loans after they made 12 months of consecutive, on-time payments. After three years, borrowers could reduce their rates by as much as 150 basis points.

Patelco has also put money into technology, especially its mobile application, Mendez said. The credit union is also investing in efforts to merge its online banking and mobile platforms.

2. Chop fees.

Mendez said Patelco also attracted more assets by choosing to focus on products rather than fees in recent years. In doing so, it eliminated 39 different fees, forgoing $800,000 to $1 million in revenue, she said.

"I'll tell you, giving up a million dollars of income still is very, very hard for Patelco," she said, "but what you had to have is the faith that we're going to make this up through more participation and more products and services. That's exactly what happened."

3. Reward savers.

Though financial institutions traditionally reward bigger deposits with higher interest rates, Patelco did the opposite last year. It introduced a reverse money market account in which the first $2,000 earned 3%, the next $3,000 earned 2% and the next $5,000 earned 1%. There was no application; Patelco automatically moved members to the better rate, Mendez said.

"What that did is it gave all our members the ability to earn. That has been a tremendous success for us, both in gaining growth but also in gaining members," she said.

4. Stop prioritizing product sales.

Getting rid of product-sales incentives and changing marketing messages have also pumped up assets, Mendez said.

"We shifted marketing language to be much more about the member and not making a product sale," she said. "We also really shifted the way we reach out to members. Not only do we reach out to them internally through the email channel or the text channels that they have with us, but we reach out to members too on social networks. Certainly Facebook has been a great outreach for us, and Pandora has been another one that has been very favorable to reach members and new members."

5. Capitalize on momentum.

Growth changes how employees and members think about a credit union, and that in turn can produce more growth, Hanelt said.

"You don't get that much scale going from $4.8 to $5 billion; that isn't the answer," he explained. "What you get is confidence and a belief that you can do it, you're a winner, you're on the right track."