Umm, why do I actually believe? Need help explaining

Salam alaikum, so I was born Muslim and as a kid, I just followed what my family taught me. But when I grew up and started being accountable for my deeds, I began searching for real proof that Islam is the truth. Alhamdulillah, I never had doubts, but I wanted solid answers. And by Allah's mercy, I found them. I'm still a Muslim, I deeply love Islam, and I want to invite others to it. The problem is, when I'm just reading and reflecting, I get it. But in the middle of a discussion, my mind goes blank. I forget all my reasons. So please, what do you say when someone asks: 'Why do you believe?' I'd really appreciate your tips-what works for you? Jazakallah khair.