Adults want to learn some basic self-defense martial arts and so on. What's so good about that?

Because of age and time, adults can't choose training like majors. Then there are probably two options.

Sanda and traditional martial arts.

Sanda fighting class: just take time to go to the boxing gym for training every week, and the coach will arrange the content for you. The advantage of this choice is that you can exercise your comprehensive quality, increase your comprehensive strength, play related qualities, make progress after one day of practice, and you will soon be able to defend yourself. The disadvantage is that being an adult is not suitable for long-term persistence, because fighting activities, even if amateur, have great training intensity and physical condition varies from person to person. Such as; Sanda, muay Thai, free fighting, karate.

Traditional Wushu: this should be trained frequently and persisted for a long time. Exercise at least five days a week for at least two hours at a time. The advantage is that if you practice both inside and outside, the overall physical quality and the functions of the internal organs can be strengthened and you can practice until you are old, because everything in traditional sects starts from the foundation and there are many practices in mind. The disadvantage is that you can't work hard in a day or two, so pay attention to the balance between internal and external training. For example, if you are weak, the master will let you start with the basic Gong Zhuang or some health care techniques and teach you several Sanshou martial arts moves every day. But actual combat is also possible. Such as: Tongbei Boxing, Shaolin Boxing, Octupole Boxing, Bouncing Legs, Xingyi Boxing, etc.