It's important that you do it for yourself above all else. With creative projects like comics, if you aren't personally interested in making it, you won't feel like finishing it. For me, I make sure I care about my story and the characters enough to see them through to the end. I talk to as many people about it as a can, anyone who cares enough to listen, and that usually helps me get more motivated to keep working on it. I think it's better to focus on keeping your work relevant in your own eyes rather than trying to make it relevant to everyone else.
And don't worry about being too similar to something else. Make a story you're happy with, no matter what it closely resembles, the story is YOURS and that makes it special and different. It may be like Kamen Rider, but it's not. You made it your way and that's all that matters. You're allowed to wear your inspirations on your sleeve as well, doesn't matter what they are. As Ethan Becker says, there's no such thing as a 100% original idea, you take ideas from others, mix them together, and come up with something new and unique to you.
Speaking of inspiration, I've heard it's helpful to get inspiration from wherever you can whenever possible. Listening to music, going for walks outside, reading books, watching shows, etc. Creative minds are fueled by the inspiration they get from the world around them. Without any inspiration you can find it difficult to create and you may find yourself discouraged and unmotivated, so keep that in mind if you haven't until now.
In conclusion, don't force yourself to work on a personal project you have no passion for, inspiration is important for motivation, and being similar to other works is not a problem.
I hope this was helpful. I didn't read the other replies, so I'm sorry if I repeated anyone else's points. Good luck with finding your motivation, dude. It's sad to see when other creators give up