As a fitness professional and veggie I hear these questions all the time. Often this even accompanies stories by people who were once vegetarian but were not able to maintain the lifestyle because they claim they weren't getting enough protein (and iron) and were tired all the time.
I can tell that when I became vegetarian I had more energy, when I became vegan I had even more strength and vitality! So trust me it's not the veggie lifestyle that makes you fatigued it's the way you eat and what you it. Just because you have eliminated meat does not mean that you are eating a healthy lifestyle.
So where do I get my protein from? Plant-based foods, nuts, lentils, beans, grains, and I use these and more to also create amazing protein shakes, bars and more for before and after my work-outs.
How much protein you need really varies by individual and activity level, and yes, you do need extra protein if you are working out.
If you were to read anything by vegan athletes and bodybuilders Brendan Brazier or Robert Cheeke you would quickly see that they both see the importance of fueling the body with protein, especially after a work out.
Your muscles need protein to repair and grow after a workout and as I've said before, the sooner after a workout the better. After all if your body can't get the protein from what you feed it after a work-out it will take it from the stores you have which often is the very muscle you are trying to build. This can cause you to become protein deficient and make it hard for you to gain muscle size and definition. This becomes a sort of self-cannibalism as the body eats it's own muscle and protein stores.
If you have a good pre-workout meal and a good post-workout meal or shake, not only will your recovery be better but so will your healing of the muscles you've worked.
I have perfected some pre & post workout meals and shakes for myself this year that I find I now no longer have muscle pain and soreness from workouts and have more fuel and energy to workout harder and longer.
I know this will continue to be a topic of conversation, and I will continue to try to enlighten you.
Vegan peace and love!