Just going on what you said in your initial question, your asking for energy from your food for working out.
Whilst food can give you energy, it wont really "fire you up" unless your taking caffiene and many B-vitamins along side. I'd recommend that before you even think about what to eat, you make sure your sleeping enough, drinkin enough water through the day and if things are stressful at work, you have a way to talk about them or deal with them as emotional stress can tire you out.
Foodwise, what do you eat otherwise in the day? are you hungry before you workout? what does your workout consist of? (eg resistance, cardio, weight training, HIIT.....?) would be helpful in order to give you the best answer.
If your looking for something to stop you feeling hungry and maybe lift your mood a little, maybe a banana, yogurt and milk shake (whisk together) would be fine to line your stomach if you've not eaten for hours and want something sweet that is easy to drink. A protein shake would be an upgraded version of this but depends what your asking for from a workout, its not worth wasting £££ on daily protein shakes if your not really into building muscle or intense cardio and if your already eating in the day (you don't say either way) your likely already getting your vitamins in what you already eat.
Before my workout I eat a protein bar, but thats my lunch, its a protein bar as I don't trust myself not to overeat (do it all the time) and so make a workout too difficult to complete or pointless in the face of too many food calories! Each to their own, I know there are healthier ways of going about this problem, but this works for me. Maybe try a few things out and see what works best for you. Theres no wrong or right answer, its just what feels best for you, but do try to vary what you do, it healthier!
