I've worked with a couple students recently who had a lot of trouble racking the slide. Racking the slide is less about strength than leverage. You can do it, it just takes practice.
First, make sure you are in your workspace, close to the body, upper mid chest. Think of where you would hold a jar with a tight lid to open it, that is where you are strongest. Hold the gun in your strong hand, come up and over the top of the slide with your weak had, grasp the rear of the slide firmly and pull back while pushing forward with your strong hand. When it is a far back as it will go...let it fly! Yep, let go. The slide is designed to do that.
You can do it, it just takes practice. It can be harder on the smaller guns, the "pocket pistols", mostly because there is less to get a hold of, but with practice, and patience, you can do it.