You can start from scratch
You don't have to be in great shape at the first class. Fitness, strength and fitness are built gradually during regular exercise.
Efficiency built gradually
The instructor shows you the exercises and helps you adjust them to your abilities. What matters most is commitment and willingness to learn. Everyone started somewhere, maybe now is a good time to start Your first training?
You don't have to prepare for months
If you're putting off your first workout until you're in better shape, you can start by talking to an instructor. Classes are a place for gradual learning and skill development. There is no need to pretend that you know the exercises - knowing that you are starting from scratch helps to better guide you through the first steps.
What to tell the instructor?
Tell me if this is your first contact with martial arts or you're back after a break. Mention if any movements are difficult for you or you need a calmer explanation. You can also say what encouraged you to train: movement, self-defense, concentration or learning a new activity.
How to approach the first weeks?
Focus on listening carefully and learning the basics. Instead of expecting yourself to be at the pace of more experienced people, focus on understanding the task correctly. Ask when something is unclear. Your own learning rhythm and regular contact with the instructor are a better starting point than the pressure to know everything at the first class.