How effective is backtesting?

On a losing streak in this week. Decided that I will backtest from July 21 data. Choose this phase as it is a similar complex corrective phase which we are currently in. I btst/swing trade stock options. How effective is backtesting and will it help me improve my win rate.

Ps. Tried it a few times before making this post and I noticed that my mindset while back testing is similar to playing a game and like I went from +50k in profits to 0 in almost 10 trades. Any trick to avoid this and make it feel like real trading?