Welcome to the forum Scuba. I too was very active before, work-a-holic, tennis, golf, scuba diving, fishing, bicycling, name it I probably tried it. Remember you are not alone, we have all been there one way or the other.
After you have had time for it to sink in and reflected on WHAT NOW?
Live every day and focus I mean on living. Do the things you wanted to do but have put off waiting for a better time. This is the that time. Before you get too weak travel, visit places and friends you have always wanted to go see or do. Take advantage of making memories for your family, friends, and for you.
If you never took the time to consider what is REALLY important in your life, now is the time. I encourage you to make your peace with God and with family and friends. Our clocks are ticking every minute, closer to the time when we will pass from this life to the next.
There is truly a God and He loves you and knows just where you are, trust Him. He is faithful to bring you through this with a wonderful testimony of His loving grace. He has a plan for each of the days you have left. You are not alone.
I pray His angels are encamping around about you and delivering you into His peace during this most difficult time in your life.
To God be the glory, for great things He has done.
God Bless,
Capt. AL
God's servant till the end.