Curl PHP to API with HTTP Header and Post data conflicting

I am making a curl call using PHP to a PHP based URL and getting into some problems.

Please note that the when I add the Content-Type in the header, it causes the endpoint not to read my params at all.

Any help is appriciated.

Here is what I am doing and the result I am getting:

With Header but no Content-Type in Header:

$curl = curl_init();
$params="action=start_day_activity&woid=23";
$headers = [
    "Authorization: Bearer $token"
];
curl_setopt($curl, CURLOPT_URL, $api_url);
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_HEADER, 0);
curl_setopt($curl, CURLOPT_POST, 1);
curl_setopt($curl, CURLOPT_POSTFIELDS, $params);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);
$result = curl_exec($curl);

// Status 200 // $result becomes = "{"flag":0,"message":"Token not found in request","data":[]}"

With Header with Content-Type in Header:

*$curl = curl_init();
$params="action=start_day_activity&woid=23";
$headers = [
        'Content-Type: application/json',
        "Authorization: Bearer $token"
];
curl_setopt($curl, CURLOPT_URL, $api_url);
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_HEADER, 0);
curl_setopt($curl, CURLOPT_POST, 1);
curl_setopt($curl, CURLOPT_POSTFIELDS, $params);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);
$result = curl_exec($curl);*

// Status 200 // $result becomes = "{"flag":0,"message":"No Request.","data":[]}"