I was surprised how well it worked. I had forbidden myself: Reddit, Hacker News, Porn, facebook wall (events and so on still allowed), and youtube (with exception for academic lectures). What I had learnt:

• Knowing this is a ritual done together helped me.
• I was suprised that it was not tempting to go to reddit/HN/FB. Except when I wanted to kill some time every few days. But then it was still easy to just read some articles from getpocket.com.
• Often, during evenings, I crave instant gratification that I used to get on these websites. Now I usually go for a walk, or watch some lecture. I want to find something better to do when I am tired. This is frustrating
• I still watched porn a few times. That is only violation of this lent. That was when it was evening and I was very tired and really strongly wanted gratification and was horny. But still I had watch porn much less than I would be otherwise.
• I do not learn much useful from HN.
• I want to continue like this, but I am not sure how to make me follow the rules.