Hello !!
What honesty!?!
You obviously know the benefits of exercise - esp for increase in energy levels!
You need to find a fun way of getting fit .
If you are enjoying your workout then you will not feel this way about exercise.
I suggest maybe dance - like zumba or depending on your fitness levels - pilates perhaps ?
Light headiness is also related to a release of toxins in the body.
However for all the reasons you have mentioned - you really should consider a Persanal Trainer.
A Trainer will keep you motivated and ensures a variety in your workouts!
Should you prefer I can teach you the exercises best suited to you in 3 sessions and you can maintain the programme .
Send me a mail should you be interested .