You are certainly capable of doing hard things. The problem is that you may only feel like doing it on certain days. Therefore, it would be helpful that many of the good things you do are easy.
We are all unique. We have different personalities and interests. You will likely be more successful if you choose to create a habit that is enjoyable for you. Just because running is a very effective exercise chosen by many successful people does not mean you should run. If you find running boring, you should do something else to get your heart pumping. Forcing a habit upon yourself will be a life struggle. The important thing is to try new things and find what works for you. You can explore different activities and turn what you enjoy into a habit. Always remember that you are unique.
When you are just starting a new habit, you are more likely to continue if it's easy. Doing difficult things requires a lot of willpower. And nobody's resolve is unlimited. For example, if you want to create a habit of running, you can start with short distances. You are more likely to stick with it because the amount of time and effort required is lower. After running becomes a habit, you can then gradually increase the distance. Going from 0 immediately to 100 is unlikely to succeed. But you can take intermediate steps to let your mind and body adjust.
You can make your life easier by choosing a habit that fits you and starting small. Doing this will improve your chances of creating a routine that sticks.