Shortcode Within A get_post

Let me see if I can explain this.

1. In my template I am using this code to display a single post:
$my_post_id = get_post ($postid);
$my_content = $my_post_id->post_content;
echo $my_content;

2. There is a shortcut inside of the post that I am pulling with the above function. But when I pull that post using the get_post listed above, it gets returned as a string and the shortcode isn’t executed. So when I do the get_post above, it ends up displaying the post as:
Blah blah blah [my_shortcode_function foo=”bar”] blah blah

Any clues on how I can modify the get_post call in order to not turn any shortcodes into literal strings?