While loop with if bash

This maybe a duplicate of Bash loop control while if else with a return. The method that I am inquiring about might be different. Here's my challenge.

I want my bash script to look for a string in a file. If the string is not found, I want it to say so, wait 10 seconds, and keep looking for the string. Once the string is found, I want it to exit and do other functions. I am having trouble placing the logic of while and if. Code below:

 while ! grep -q Hello "filename.txt"; do
  echo "String Hello not found. Waiting 10 seconds and trying again"
  sleep 10
   if grep -q Hello "filename.txt"; then
    echo "String Hello found in filename.txt. Moving on to next procedure"
    sleep 2
    return 0
   fi
   #do other functions here
 done
exit