Vegan Bodybuilding & Fitness

Ok so here is the situation with me:

I am 23, 135lbs, very toned with little body fat but also little muscle. I have tried in the past to build muscle with very little success. I won't say I am giving up on muscle building, but I want to try a new approach to fitness.

I have pretty terrible endurance. I'm used to working out for less then 30min 3x a week. So endurance is my new goal. BUT I do NOT want to get any skinnier then I am! I really can't afford to lose any more weight. Here is what I am thinking:

Sunday- Hot Yoga
Monday- Spartacus Workout ( http://www.menshealth.com/spartacus/workouts/ )
Tuesday- Dynamic Apnea (http://en.wikipedia.org/wiki/Dynamic_apnea) / swimming
Wednesday- Spartacus Workout
Thursday- Rest
Friday- Spartacus
Saturday- Dynamic apnea/swimming

How does this look to people? Remember, I want to get fit and get better endurance without getting skinnier! I posted two pics so you could see what i look like now.

For me the best way for improving Endurance is running. Especially high intensity sprinting.
I know the spartacus routine it's pretty cool one. But it's mainly for strength and cutting.
If you wanna gain more muscle mass. You'll need to up your daily Calories and lift as heavy as you can.

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I would never settle for anything less than I could be - Tony Robbins

Thanks for the advice

I would appreciate input from others