Broja has been sidelined since he ruptured cruciate ligaments in his right knee during a friendly against Aston Villa in Abu Dhabi in December.
The 21-year-old has been ruled out until next season but is back in light training and making good progress in his rehabilitation.
“I still haven’t got my head fully around it,” Broja admitted in an interview with the Chelsea website.
“It does play on your mind. It was a big shock because I have always been quite a healthy lad, and have had just had a few minor injuries here and there. It was an even bigger shock to my mum and dad, because they have so rarely seen me injured.
“After surgery, I was bedridden for about two weeks. It was one of the worst times of my life. It was horrible. I couldn’t get out of bed. My mum was running round the house to get me tablets and give me my food. It was a struggle. You almost feel useless. You want to be able to do stuff, but you just can’t.
“I couldn’t sleep. I was in pain. The day and what happened played on my mind constantly. I was thinking about ways I could have avoided it, even though I knew that wasn’t a good thing to do.
“I had to take a step back from that. It was something I had to move past, start just focusing on getting back fit. As they say, the comeback is going to be better than the setback.”
Broja played 12 Premier League game this season before his injury, 10 as a substitute, and scored one goal following a successful loan spell at Southampton last season.
The Albania international is targeting a return next season.
“Three weeks ago, I got back out on the pitch,” he said. “That was one of the best days. It makes you happy every time you hit a milestone in your recovery. It gives you an extra boost.
“There are some days when you come in and you feel like it’s not getting any better, or any worse. It’s just the same. I’ve been miserable, a bit moody. But now I can see the journey from where I was, to where I am.
“I’m kicking a ball, moving, changing direction. You have to find the balance between how much load you put on the knee, and how much you take off it. So it’ll be a while until I can start doing sprints, jumping, that kind of stuff, but I’m really happy with how it’s going.’
Broja added: “I have learned a lot about myself, physically and mentally
“I have always been thankful for the position I’m in as a football player, but this has made me even more thankful. You never know when it can get taken away from you. We’re very privileged. I don’t take anything for granted now.
“When I was bedbound, I was thinking a lot. I missed the sport a lot. It reminded me how much I cherish football, how much I love it. It was a big injury, but one I can recover from. I’m giving it my best, working my hardest to get back as quick and as strong as possible, and I’m so thankful for the recovery and support I am getting from the club.”