keeping out negative opinions

I was talking to a co worker today (friend) letting them know that I have made the decision to go part time at work if my work will allow it, to give me more time to work on my coaching business. Immediately they start saying are you sure this is a good time to give up your job and benefits with the way the world is right now. And I 100% did not believe them, and I said yea I can see how that is your opinion, but I choose to believe there is no better time to start it than now. I say I don’t believe them but then I get this little feeling in the pit of my stomach, but what if he’s right. I had originally decided if they weren’t going to allow me to go part time then I would put my notice in but now I am second guessing that. Now that I have a little doubt in my belief that this is the best time to do this, I’m feeling a little hesitant. I guess I just need to come up with another belief/thought.