I've been trying to wrap my head around this expression recently. I suppose one wouldn't be if their every waking moment is coursed with having to do something. Someone used this expression in reference to me.
And now I will explain why they are wrong. I am a walk in the park if you only have to sit and watch television or play endless games of Spider Solitaire on the computer. I am a walk in the park if you are allowed to nap at will, and you don't HAVE to do any work in the house you live in. I am a walk in the park if I tend to everyone's needs and you don't have to. I am a walk in the park if the landscape is taken care of regularly and you haven't hired anyone to do it. I am a walk in the park if the dogs you claim to love are exercised daily and you didn't hire a dog walker or a kennel service. I am a walk in the park if you have dirtied up something that I spent hours cleaning and I didn't scream at you.
I am a walk in the park if I spend 40+ hours a week working a paying job. I am a walk in the park if I tend to my own every need and don't rely on anyone else to do things for me. I am a walk in the park if I can do anything without someone telling me what to do. I am a walk in the park if I tend to the other relationships in the family.
Maybe you should take a walk in the park and see if it's any different than what you do now.