After missing the last two months with torn ankle ligaments, the 25-year-old played 45 minutes of struggling Dortmund's 1-0 friendly win over Romania's Steaua Bucharest in Alicante at the end of their Spanish training camp.
"I'm very pleased with the way the injury has healed, I can do everything I did before it happened," Reus, who missed Germany's World Cup triumph last June with an ankle injury, told German broadcaster ARD.
"It's important that I can look ahead, be fit to help the team move up the table," said Reus.
"It's important that we now pick up the points to boost our confidence again."
He says he bitterly regrets the scandal he caused in December when it was revealed he had never passed a driving test, despite having driven for years, which led to a record €540,000 fine.
"If I could undo this, I would, but I can't and therefore I have to stand up and take it on the chin," he said.
There was some bad news for Dortmund boss Jurgen Klopp as both midfielders Sebastian Kehl and Kevin Grosskreutz picked up injuries against Steaua.
Dortmund are away to fellow Champions League side Bayer Leverkusen when the Bundesliga resumes on and are desperate to pull themselves up from 17th in the table after a disastrous first-half of the season.
Despite winning their Champions League group, Borussia lost 10 of their first 17 league matches – the worst record in Germany's top flight.
They face Italian league leaders Juventus away in the first leg of their Champions League last 16 clash on with the return leg in Dortmund on .