Imagine something you did while you were younger was being recorded. Okay, so it turned out to be awesome. This is how looking back at the original Star Wars films is like for Harrison Ford. Now, imagine looking at a different incident, it's you, but you didn't actually do it. Weird, right?
In an interview during the Star Wars Celebration, Ford was asked if he was excited about the Han Solo movie and he jokingly said, "Not really."
After a bunch of laughter, he followed up saying, "Of course I'll be watching it as a fan, but it will be weird."
Essentially, seeing his character running around not being played by him is a weird concept for Ford, and probably would be for anyone who is 40-years deep into a character. When talking about the new actor, Ford said, "I’ve met the fella [Ehrenreich] who’s gonna play the younger Han Solo. Wonderful guy, very sweet, and a very good actor. So I’m delighted in the choice.”