Question 

My mother passed away a year ago and I think about her every day. Truth be told, I think about her multiple times a day.  Every time that I do something the way she did like, planting flowers, using her favorite cleaning product, or making a meal, she pops into my mind.   

People say you had her for so long, as though I should be satisfied with the length of her life. I even find myself saying that to others. My mother did have a very long life. She may have been in the top 1% when it comes to lifespan.   
Gosh, I miss her anyway. I thought by now that feeling would go away but it has not. Should I be content that my mother had a long life and just let her go as people suggest? 

Answer 

It is a funny thing that we say to each other, minimizing grief based on lifespan in our condolence. As you mentioned we even say it to ourselves and others, as though the age someone lived to should determine how much we miss them.   

We say that someone had a long life because it is true. Somehow, we think there is comfort in those words, but it really is only suggesting to another person or even yourself that grieving the loss is unnecessary because they lived a long life. It is simply an attempt to nullify the feeling of loss as though a long life should mean no grief. It is not so. We miss people regardless of lifespan.   

Please understand that people simply do not know what to say when someone dies and yet they want to say something comforting and consoling. Give them credit for trying to be of comfort and try your best to accept that is what they meant to do. Humans have this need to use words to express our sympathy and at times when we do not know what to say, we fill the void with interesting comments. The length of a life does not factor into the loss. A long life does not take away your right or need to grieve the loss. When a life is long, the death is rarely a surprise and therefore not shocking as say a heart attack while out running at the age of 40. There are just as many odd comments with condolences for a 40 year old, just different ones.   

As for how you process your loss, thinking about your mother as you go about the tasks you do each day is quite common. You will carry this loss with you for some time and your mother will pop into your thoughts frequently during that first year and likely for some time after that. The loss will never completely go away, nor should it. If you can hold memories of the past, your mother will be part of those memories. The pain will lessen over time. The occasional tears will be less frequent. The loss will always be there, just less and less intense. 

Give yourself this time to think about your mother, share stories with siblings, talk about her, and grieve. It is quite normal to miss your mother regardless of her lifespan. Others whose lives she touched miss her also.