I have also pushed myself to do things since losing my husband in 2011.I try and think in terms of him being with me in spirit so have largely chose things we enjoyed together and things I know he would have liked to do.Sometimes I do feel he is there,not always though.Coming home and back to normality I still find far more difficult.I tried joining a few local things,just because that's what you're "supposed " to do.They didn't work out,I didn't fit and have since realised the things worth fighting and overcoming hurdles to do are only those I want too not things others think I should.In time the trip or event you want to do with U3a will come along,but don't rush to just do anything for doings sake pick your battles in other words.
It is still early days and as shock and disbelief turns to horrible reality loneliness and longing can become very intense no matter how hard we try to fill the time up.I think sometimes we have to just allow ourselves to grieve.