1) Society changes. After breakup with USSR in 1990, all collective farms were dismantled and majority of industry closed or restructured what caused a lot of people lose jobs and forced to change profession. This was hard/impossible for some, especially older people, who were used to work the same job for years or even the whole life. In first years it was partly offset by the excitement of independence, but as years went by, excitement faded away and problems remained. Even bigger impact was the mental change that you are responsible for your and your family well being and there's no longer government that takes care of every aspect of life. Some people still can't wrap their minds about this fact and blame government everything. Also, there are very few jobs in smaller towns/villages, so those who could, already fled to cities or abroad and those who couldn't are doomed to poverty which leads to the second reason.
2) Alcoholism. Lithuanians, as most northlings, are overly serious (if you smiled to strangers, locals around usually look suspiciously or even aggressively) and prone to depression what combined witch financial difficulties many faces (caused by 1) often leads seeking relief in alcohol that worsens depression even further.
3) Identity crisis (not discussed very often, mostly my thoughts). We are still in transitional state, where no longer belong to east, but not yet fully converted to western way of life. We lack self-dependence, motivation, initiative and risk taking attributes common for democratic westerners and keep looking back for somebody to lead and hold hand (the same strong leader cult as in Russia today). We are like a teen who fled his parent's home -- don't know where to go and what to do.
These problems aren't unique and many post soviet countries have similar issues, though some simply cope with them better than others. Anyway I'm optimistic, because progress can be clearly seen in many areas (Lithuania has one of the fastest growing economies in EU) and many young people are doing better than their parents.