The 28-year-old was released by Coventry City at the end of last season, but has since linked up with Charlton, impressing in the early stages of the Championship season.
He told the South London Press: "When I found out I could go on trial with Charlton, then I had to give it a go. I had confidence in myself to do it rather than sit back and take an easier option.
"I wanted to play in the Championship - I knew I could still do that. Football has changed a lot in the last few years. There are so many players out of contract and without a team, because all over the country clubs have tightened their belts. It's a lot harder to get anything. I was happy to come in and prove myself.
"When I got the chance to try and get in the team and earn a contract, I grabbed it. Sitting here now, it has worked out well because I'm playing."
Wood started his career at Sheffield Wednesday.