How to have patience with your kids?

How do you handle anger/frustration when it comes to kids? I have such a quick fuse with my kids and my dogs lately and I just cannot cope. My kids are 3 and 1.5 & I am really struggling with trying to correct behaviour and feel genuinely overwhelmed.

What helped you? Therapy? Meds? How did you learn to have more patience? Every day I lose my patience and as soon as they go to bed I feel absolutely terrible.