While on a Keto Diet, do not assume that it's best to simply give up on exercise. It would remain an important part of maintaining your health. However, what you could easily do is, include low-intensity exercises such as walking, light jogging, or even gentle yoga for about 30-45 minutes daily. The idea is to maintain a steady-state of physical activity and avoid workouts that demand a sudden burst of energy.
Although it may seem counterintuitive to exercise when lower back pain is causing you grief, the right kind of movement can help eliminate the discomfort. It’s always important to consult your physician before you engage in exercise when you have pain, but this conversation is well worth having if you’re suffering.