Find people that laugh at everything and surround yourself with them. /s
I've had people tell me I should do stand up and I'm like lol no. My comedy comes from the top of my head and acting out physically. I feel like if I had to sit down and write out my jokes for a 15 min presentation they would all fall flat. I just do better with quick responses to things around me. Also, many of my jokes revolve around sexual ideas and themes, so maybe find a theme you enjoy and make it your strong suit. Good thing about sex is it can be applied to about anything around you lol.
Edit: since you feel more comfortable with your writing of jokes, maybe try to work them in a way you would say them to an audience. Maybe tell them to yourself in a mirror and change it to better suit it to that. This is how I would work on bettering my promos when I was wrestling.
Many people in comedy can't do it all. Some are better at standup, and other like me do improv better. Just got to find your calling and always be willing to learn from mistakes.