gzip files inside directory

Hello folks

I hope every one is fine. I need to ask one question.

I have directory

/xx/abcd/data/

inside that data there are files like

11.txt
23.txt
12.txt
*.txt [all are txt files]

i want that i will do compress each txt file inside that directory /xx/abcd/data/.
But it will not gzip data directory, only do gzip like that

cd /xx/abcd/data
gzip -9 *.txt

Please suggest how can i make it through shell script and need to automate it with cron.

Do the same in the script as you are doing now.