I would suggest being careful with this kind of response. It's the kind of thing you can tell a close friend face-to-face and it might be just the kick-in-the-pants they need to get them going again.

But saying it to some completely anonymous person on the Internet may be more likely to backfire than to help in the manner you intend.

There are also potential cultural differences to keep in mind as well. Brits and Americans may be more likely to respond positively to 'tough love' than Indians or others.