My older daughter and wife saw bears on more than one morning run in Sequoia National Park. I don't recall if they saw any in Yosemite. They saw baby bears on or near the paths and the mother no far off. My family would just stop, turn around, and go back the other direction. We typically ran in the parks first thing in the morning when there were few vehicles in the parking lots. I assume the bears are use to encountering people on the trails in the national parks. They saw bears on more than one morning. I never saw one. We spent 4 to 6 days in each park.