i've been training BJJ for about 2 years now i think. I currently train 3-4 days a week. Even thought there is no gi, I love to train with gi.
Motiviation? Well when i first started i was 178lb. And i was getting tapped left and right by thinner dudes. One thing i did notice though is, i would be COMPLETELY gassed by the first 3 minutes... And they would walk all over me.
So i went from, getting tapped many times a roll, to sometimes, to rarely. Then it went to NOT getting tapped and just holding my own. THAT believe it or not means you've gained knowledge and your learning. And before you know it, you will tap someone out. Maybe not in every roll, but you will.
I feel in jiu jitsu the belts are earned. I currently hold 1 stripe blue belt. And i didn't know how much i know untill i rolled with white belts, and it's a completely another game. They use so much power, and force. I rely on sweeps, and of course submissions. And some of these bigger guys, i just hold on a little untill i hit about 2.5 - 3 minutes.... They usually tire out because i give them positions where they feel they need power and waist all there oxygen and power.. Then it's a walk in the park to take their backs, or wherever.
Then i get back to the advanced classes, and it's back to normal....TRAINING. Unfortunately, the ONLY way to get better is time on the matt. Watching video's on youtube, or google, or buying $100 dvd, and books, can help... It will help a lot more if your are more advanced because you will know how to apply those subbmissions or sweeps to your rolling. If you are a beginner, you will look to do ONE move, and you will get stopped almost every single time, and get subbmitted.
Every now and then we get these guys who watch ufc, pride, kot, and want to mimic those moves, and think it's all armbars, guard, and guillatine... BUT after training they didn't expect to get purples in the shines, arms, neck chokes that leave hickey like marks, swollen fingers from grabbing on to the gi, knees that have scrapes, and are soar, etc... Then they quit. After you've been there a while, you will have harder grip so your fingers will be used to being crucket (spell?), your knees will built tollorence to the ground, neck chokes aren't all that back, etc...
Just relax and spend more time on the matt, that is really the ONLY way to progress. Time on the matt. Good luck.