How to add a directory to my path?

 How do I add a directory to my $PATH in Ubuntu and make the changes permanent?

For complete newbies (like I am) who are more comfortable with GUI:

1. Open your HOME folder
2. Go to View > Show Hidden Files or press Ctrl + H
3. Right click on .profile and click on Open With Text Editor
4. Scroll to the bottom and add PATH="$PATH:/my/path/foo"
5. Save
6. Log out and log back in to apply changes (let Ubuntu actually load .profile)

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