How do I be more positive ?

Any advice on how to be more positive ? I’m 16 years old and I overthink so much especially at night time when I’m alone. I have anxiety and it’s ruining my life, it’s not that bad so I’m not on any medication for it but it stops me from having conversations with people I’m not really close with and I’m very quite, I need other people to ask questions for me or get me my food ect. I wish I could be more independent and confident but I can’t so I’m looking for advice, it would be much appreciated x