1. To start traveling or moving at a consistent, maintainable, and fast speed or pace. We started out the run slow but reached our stride as we came to the park.

2. To become proficient, comfortable, or confident doing something. Once you reach your stride at your new job, I'm sure your boss will be very impressed with you. It took me a while to get used to writing non-fiction, but I feel like I'm really reaching my stride now.