Maybe with habits and tasks done you win points, and with that points you can buy rewards. Would be good for motivation to do habits and tasks you do not want to do.

It is good for be productive, because for example: if a person have to do a task that do not want to do, like "sweep the floor", then a good way to push that person to do it will be: if that person know that if he/she finish the task, then he/she will can buy a reward that would be maybe "Eat the chocolate i left on the fridge" so having the task finally done and also can do something he/she likes, would give more desire to finish more tasks, because the brain relate the good feeling of the reward with that task or with "doing tasks". and also if the person do not do the task, then he/she will can not but the reward, so neither eat the chocolate.