Maybe he should taking vitamins if he finds that he is always tired and go to his doctor for a physical.
You can role play, used toys, massage lotions, play some sex games, foreplay, and try some new positions for sure.
<Edit> When trying a new position don't think your going master it your first time around. Practice makes perfect! You and your boyfriend have to work together and in time you will get better at it. Here go some sites that may help with positions and they have photos and explain it too.www.sex-techniques-and-positions.com/
www.sexual-health-resource.org/sex_positions.htm