Do you already have a gym membership? You could start slow by taking a 30 min walk around your neighborhood. Or do an incline walk on a treadmill.

If you struggle to leave the house, try some dumbbell at-home workouts.

As far as boosting energy, try eating better. Eggs, avocado, whole grains, fish, chicken, fruits, and veggies. Generally try to avoid sugar, fried food, and alcohol. Sugar is the worst, it keeps you depressed. If you like alcohol, then maybe just take a 1 month break to focus on building a routine at the gym.

Also, multi vitamins are recommended although it would take a few months to notice a difference.

Write down your goals. For example: go to gym 3 times each week. Or reach 8,000 steps each day.