I think i have plantar faciitis and i know it's because of gaining so much weight. how can i jog if it is always aching everytime i sit or lay down?

Plantar fasciitis: If it is indeed plantar fasciitis, continuing to exercise without treating the underlying problem isn't going to be helpful. Initial therapy is geared toward improving pain and preventing reoccurance. Try anti-inflammatory medications, home stretching exercises and arch supports for your shoes. See a podiatrist if the problem persists.

See below: Try different exercises than jogging, such as swimming or eliptical, or bicycle.