Oh to be so young again...
but seriously, I'll be in my early (mid? eeeek) 30s when I
start school. I totally get the point about saving for retirement, but depending on where you're starting from (and other factors like SO's income/debt ratio, etc), it can still be doable to specialize. Keep in mind that there is usually also a small upside after that residency in terms of earning potential. If you want to do shelter med or GP, then by all means do those because they are both
great, but don't write off specialization just because you'll be a little older.
Now on the other hand, if your concern about doing a residency is how to actually physically handle one while 1) needing 9 hours of sleep per night and 2) having a family/young kids, then let's have a pity party together. I'll start: