Our everyday work is becoming increasingly complex and cognitively demanding. What we pay attention to during our day influences how effectively our brain prepares itself for action, and how much effort we apply to a task. To address this issue we present AttentivU -a system that uses wearable electroencephalography (EEG) to measure the attention of a person in realtime. When the user's attention level is low, the system provides real-time, subtle, haptic or audio feedback to nudge the person to become attentive again. We tested a first version of the system, which uses an EEG headband on 48 adults over several sessions in both a lab and classroom setting. The results show that the biofeedback redirects the attention of the participants to the task at hand and improves their performance on comprehension tests. We next tested the same approach in the form of glasses on 6 adults in a lab setting, as the glasses form factor may be more acceptable in the long run. We conclude with a discussion of an improved third version of AttentivU, currently under development, which combines a custom-made solution of the glasses form-factor with built-in electrooculography (EOG) and EEG electrodes as well as auditory feedback.