Conquer your fear of heights!
This is coming from someone who is terrified of heights, has asthma, and is not in the best shape. Trust me, if I can make it to the top, anyone can do it.
Although it took me longer than most people, this is definitely a short and doable hike. There are hand rails for most of the hike but there are also some exposed areas with just rocks used as barricades. Some areas can get narrow when there are lots of people passing by. You can stop at certain areas, rest, and continue. Just take your time...let others pass if they're in a hurry.
We went in October and the weather was hot. Great cardio workout! You'll break a sweat because it's mostly stairs but just bring a light jacket if it gets windy. Also, bring a hydration backpack, sunblock, and your camera. This was one of my favorite hikes in Sequoia.