The total fertility rate is a measure of the number of children that would be born if all women lived to the life expectancy age for the given country in which they live.

Although this may be the opposite of what you think i will say it anyway. you were brought into this world for a reason and you still have soo much ahead of you. not everybody has an opportunity of living a great life, but it doesn’t give you a reason to end everything. somebody in the world loves you, and imagine what you would do to them if you left forever.

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.