newtonsoft json serialize camel-case

I'm try to serialise an C# object to json by using Newtonsoft.Json.Serialization but it's returning name of properties as Pascal-case.

For an example consider the following C# class:

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

By default, when returning an instance of this class from a class as JSON, it'll be serialized in the following fashion:

{
  "FirstName": "Me",
  "LastName": "Public"
}

I would like it to be serialized as:

{
  "firstName": "Me",
  "lastName": "Public"
}

I'm using C# code as:

var json = JsonConvert.SerializeObject(myPerson);