"Welcome To My Life" in a kid's movie?

Simple Plan released the song on September 14th, 2004, so it probably wasn't in a movie released before Summer 2004 (being generous here). Clifford's Really BIG Movie was released in February 2004.

Looking at the IMDB for the band as a whole, "I'm Just a Kid" was in Cheaper by the Dozen in 2003. They also were in 3 Scooby Doo productions around the same time, with particular involvement with What's New Scooby Doo.

There's also a possibility that the Clifford soundtrack contains something that sounds similar to Simple Plan.

What is it?

Here is the film's soundtrack listing according to Wikipedia:

• "Until I Go" by Kyle Gordon
  
  
  
• "Party Time" by Jody Gray 

• "I'm Not Scared Anymore" by Renee Cologne
  
  
  
• "You and Me" by Jody Gray
  
  
  
• "Big Time" by Jody Gray
  
  
  
• "Larry's Amazing Animals" by Jody Gray
  
  
  
• "Until I Go Reprise" by Laura Berman
  
  
  
• "Home Where I Belong" by Romaine Jones

The film's soundtrack was composed by Jody Gray (he also performs about half of the songs listed here), yet I can't pinpoint to the one you are looking for, but at least it's a start.