Struggling to be patient with my kids lately

I've been really impatient with the boys this week, yelling over small stuff and not showing them the love and grace that Jesus showed us. I feel like I'm failing as a dad and a Christian. Been trying to pray about it but some days the stress just takes over and I snap at them. How do you all keep your cool and lead by example? I know they're watching everything I do and I don't want them growing up thinking anger is how you handle problems.