Does anyone implement secure development lifecycle? If so, how?

So basically I am having a meeting at work tomorrow where we need to discuss how we aim to integrate secure development into our lifecycle.

I've been a developer only a few years now and we've only ever gone through the develop <–> pentest and repeat route to ensure secure development so I'm not very familiar with the technicalities of SSDL.

Does anyone here have experience in this area and maybe will be willing to share some example cases with me that would help me a lot to better understand our next steps.

Thanks.