Fortunately, my mental status becomes stable.
Talking to people, walking a lot, buying necessities, and keeping things routinely, all of those activities makes the situation better.
Research itself is fun. Yes, I am curious of science. The questions are endless; what makes differences of living and dead, why lives have diversity and create homogenous offsprings, and why the behavior of 100 cells are different from that of 10000 cells.
At the same time, 95-98% of ideas result in vein. I cannot avoid feeling guilty of wasting time, money and materials. The negative data deprive my motivation and exhaust me.
"Do not feel so serious. Research should be fun. If you don't feel it fun, you cannot continue it."
Yes, your are right.
Do not take it serious. Keep find something fun.