sometimes you loose only due having very bad dices in the wrong moment, but there will come another game where you will win due to some other guy having bad dices in the wrong moment,
sometimes you may have a loosing streak loosing 5 or more games in a row, but there will be a winning streak, the best thing to keep on motivated is to try learning from every game you do, if you loose think of the reasons in which turns did you made mistakes what could you have done better, what has the winner done better, have there been any tactics you haven't seen yet and so on .
if you come to the conclusion that you have done everthing right but though lost the game , you may just got unlucky dice or another player had a better startup position and also made no mistakes during game. well there will be games where you have the better position or better dices.
when you have more points than 1600 you should not play to much games against low pointed players , cause then a loss due to dices will hurt you very much
and never forgett the most important thing: it is just a game , and invented to have fun !!!!!!!!!!!!!!!!!!!!!!!!!