Marc Mariani never doubted his knees. So on the Shelby Street Pedestrian Bridge on Tuesday night, the Titans receiver got down on one and proposed to his girlfriend. And he got a yes. Since shattering his lower left leg in a preseason game in August, Mariani has been awaiting answers to plenty of other questions as well. So far, he’s liked what he’s seen, and heard. “In the moment, there was a lot of frustration and nervousness and me being unsure about how things would turn out, whether I could ever come back,’’ Mariani said. “But now, eight months removed, I am feeling good and feeling healthy. I’m making progress. “It has been a long journey, but I can finally see the light at the end of the tunnel.” A seventh-round draft pick in 2010 who became a Pro Bowler in his rookie season, Mariani suffered a compound fracture in his left leg when his tibia and fibula snapped above his ankle on August 23, 2012, during a preseason game against the Cardinals. He underwent surgery and immediately began a grueling recovery and rehabilitation process. Along the way, he’s also received a healthy dose of encouragement from a man who suffered the same injury himself back in 1985 — former Redskins quarterback Joe Theismann. Mariani believes he’s on track to play in 2013. He began running six weeks ago, and on April 5 he put cleats on for the first time since the injury to do some change-of-direction drills. His strength and endurance is coming back, he said, although he’s still dealing with swelling, which was expected. Mariani hopes to take part in some of the team’s organized team activities in June, and he expects to be a go for training camp. After sitting out the 2012 season, he’s as motivated as ever. “Watching the boys play on Sundays last year was the biggest motivation I could’ve ever had because I don’t want to be in those stands until I have to be. It was hard watching,’’ Mariani said. “I feel fortunate that I am going to get an opportunity to be back out there. A lot of times, guys don’t get that realization until their career is over, when they have to watch. “I got to watch this year and got a new perspective, and now I am really, really excited and looking forward to getting that helmet back on. I can’t wait. I don’t care how hard I get hit. I know I still have work to do, but I am looking forward to that day very much.”