When you play trumpet you need to rest as much as you play... play 8 measures..rest 8 measures ... easier said than done but once you get into that routine it becomes easier.
I practice intervals which should be page 125 on your Arbans.... but if you have only been playing for a year then it may be a little difficult.
Tonguing exercises in the lower register will help.
along with the other great advice given here.
keep us posted