Timid bun

I got Elliot a few days ago from a lady who could no longer keep him, he is a lovely boy but very timid. Is there anything I can do to bring him out of his shell? I have been spending lots of time just stroking him. I know the people that had him before me didn't have much time for him although he was very well cared for. He is a french lop but the biggest french lop I have ever seen. He is free range in the garden in the day which I am really happy about as the exercise will do him the world of good as he is a bit on the heavy side. Trouble is he doesn't seem to want to hop around much and just wants to hide

Tunnels might be helpful. Timid bunnies want to know there is somewhere to hide close so if they have lots of tunnels and hidey holes they can venture a bit further. A simple thing like a stretch of rope with a sheet over and the edged weighed down width bricks would make a long cheap tunnel for a big rabbit. Or leaning wooden boards up again a wall or fence.