Challenges that I've faced but now I have overcame are: 1- Lack of reliable resources 2- Poor planning of my goals 3- Some languages have hard utterances or sounds, but that's not that big problem for me because of my mother language (Arabic) which has a bunch of hard sounds like Dhad and Ain. 4- Asian languages like Chinese, Japanese, Hindi, don't use the Latin alphabet which is another obstacle. If a person speaks Japanese it can be easy for them to learn Chinese (that's not true, just a bit easier maybe), but they might not be able to learn Arabic, for example, with the same ease, but a Turkish or Iranian person can learn Arabic faster because both languages have so much in common. (Oh, I didn't know that, is it because the alphabet is similar?) These are the challenges that I think people who want to become bilingual or polyglots face. thank you for reading.