The easiest business to startup is a service business. The simple reason is that you don't need to worry about inventory, manufacturing, or shipping. You can get started with just a few thousand dollars and a few customers. The key is to find a niche that you can serve well and that is willing to pay for your services.
There are a number of ways to get started. You can start by offering your services to friends and family, or you can start small and advertise your services online. Once you have a few customers, you can begin to scale your business by adding more services or hiring additional staff.
The most important thing is to choose a business that you are passionate about and that you can see yourself doing long-term. If you are doing something you love, it won't feel like work, and you will be more likely to stick with it even when things get tough.