You might be able to use this to your advantage. Don't get the 30 hours, then noticably cut back your meeting attendance/commenting/service time starting in september. When confronted about it, say that you were stumbled by all the peer pressure to pioneer. You had prayerfully considered your circumstances, as well as applicable scriptures (Matt. 5:33,34; James 5:12; Numbers 30:2; Deut. 23:21; Ecclesiastes 5:4) and had determined that it would be best not to commit to something that you would be unable to carry out. Then, the oppressive peer pressure upon you made you violate your conscience, and eventually sin against Jehovah in being unable to carry out your promise to him.
You could even use it as an excuse to step down as an MS, because you now feel like a hypocrit, and you feel that you no longer qualify after sinning in such a serious way, allowing yourself to make a vow to Jehovah that you knew in advance that you would not be able to perform.
Good luck, buddy.