I need advices

(Disclaimer: Grammar may be bad as English isn't my first language) I'm a 16 M, and I practice and train Karate for around 4 and a half years. For context, I have always been an introvert, and since I would stay at home a lot, I would play video games all day, and one day my parents decide to make me start attending karate classes. Worked my way up for a while and I currently sit at green belt.

Now, why i require advice is because I have recently started having the idea of abandoning my "carrer" and path of Karate, but I can't bring myself to say it or do it. I live in a small place, and basically I'm known, besides as a "Computer" geek, as a karate practitioner, and my parents and siblings adore me for it.

I lost my "fire", my interest, my desire to learn in Karate, and I recently wanted to start learning Muay Thai, or Thai Box, but I can't bring myself to tell my parents and siblings, as they look up to me for representing myself in all competitions.

Now, I stand in an awkward position, unsure of what to do or say, so I need any advice, opposed or agaisnt the idea.