After making just five Premier League starts, he returned to West Ham, eager to impress new boss Graham Potter.
Ward-Prowse is now focused on showcasing his abilities after falling down the pecking order at Forest.
“It's good to be back! Obviously, it was a strange feeling and situation to leave the club in the first place, but that's football,” he said to club media.
“Even though the last few months for me personally haven't been the most productive as I would have liked on the pitch, I feel as though the whole experience off it and the sort of different tests that I've had to endure have sort of benefited me now.
"And I think I'll look back on the experience and I'll be grateful for it. It's really lit a fire in me to go out and prove people wrong.
“I just want to get back out on the pitch. I think I'm the sort of character that wants to play every minute of every game.
“That's what I've been used to over the years, so to have had that brief period in the first half of the season where I haven't, it's tested those parts of my character again from when I was younger and relit that fire inside of me to get out there and to get playing again and enter a new chapter under the new head coach with a little bit more optimism.
“When a new head coach comes in, everybody starts again on zero. There's a clean slate. So especially for me coming back, it's a fresh opportunity.
“Football is a difficult environment at times. But I've always tried to stay honest to myself as to who I am and not change. And regardless of your footballing situation, above all, the team is the most important thing.
“Whether you're playing or whether you're not, I've learned in the last few months, especially, that you have to be good around the place, even if you're not playing, because the opportunities will come at some point and you have to be ready to take them.
“My influence will hopefully help in the dressing room, but obviously, more importantly, I want to be out there and influencing games.
“I don't feel physically any different. I feel mentally stronger and I feel like I'm ready to have an impact on the club for hopefully many years to come.”