1.Nothing good happens after 2 a.m.
In the first season, Ted is in a relationship with Victoria which he feels is starting to fall apart. Meanwhile, Robin finally realizes her feelings for Ted and invites him over after 2 a.m. to “make juice”. Trying to decide what to do, Ted remembers a saying his mother used to have: “Nothing good happens after 2 a.m.” Believing that Victoria was going to be breaking up with him anyway, Ted goes over to Robin’s apartment. When Ted arrives at Robin’s apartment, he lies about breaking up with Victoria and they begin kissing. However, when Ted excuses himself to go to the bathroom to secretly call Victoria, he realizes he has Robin’s phone and Robin has answered his phone when Victoria calls. Furious that Ted lied to her about them having broken up, Robin gives him his phone telling him to call Victoria back. Future Ted reminds his kids that nothing good happens after 2 a.m. and inevitably loses both Robin and Victoria in one night.
2.Some things never change.
In the last episode, we see how things seem to become like they were at the beginning of the series. Robin returns to her apartment filled with dogs while being an international newscaster, Ted finds himself single once again, Barney return to his usual ’legendary’ care-free self and the blue French horn appears for one last time and Ted and Robin fall in love again. The vast majority of people didn’t like how the series ended, but in my opinion, I think that this sudden plot twist is yet another life lesson: some things never really change.
3.If it’s meant to be, it will be.
Throughout the show, Ted is constantly searching for the love of his life so he can get married. As it turns out, Ted only finds his true love in the ninth season. Thus we learn the age old lesson of "if it’s it meant to be, it will be’. You shouldn’t go looking for love, love is supposed to find you.
4.Everything happens for a reason
’How I Met Your Mother’ often references how all of Ted’s past experiences, both positive and negative, ultimately serve the purpose of leading him to the mother of his children and living what is implied to be a fulfilling, happy life.
5.The Front Porch test.
The Front Porch Test is Lily’s indication of how happy they would all be together once they were old, thus showing if someone’s love interest was right for them or not. The life lesson that is learned from this is that the most important people in your life are the ones you can imagine sitting happily on a front porch with when you’re old and gray. If can also be applied to help you make everyday decisions. Before making a big decision in your life, imagine that you are 80-years-old and sitting on your porch being nostalgic about your life that has gone by.
6.Never fall in love too quickly
Throughout the nine seasons of the series we see Ted falling in love too quickly and being hurt constantly.
7.The meaning of friendship
The theme of the importance of friendship is ever-present throughout the series. When Ted tells his children about New Year’s Eve, the main message is that being with his friends was more important than going to some cool party and bringing in the New Year in most exciting way. The core group in How I Met Your Mother is incredibly tight, and many episodes specifically serve to remind us how valuable true friendship is.
8.’Wait for it’.
Sometimes in life you just have to wait for things to happen and not rush for them to actually happen. Some things will turn out to be ’’legen-wait for it…-dary’’!