Do you have a regret?"That was a wrong decision and I regret it". Many people will say this when the consequence of an important decision gives negative results. This happens in life and not all decisions give us fruitful results. After all, we are not programmable devices, we are living beings and in life, many times we make our decisions depending upon many 'if' and 'but'. For example, parents may say "if you studied well you could have been selected for the course". "But you never listened to us and see your situation now". "This will remain a regret in your life'. That guy loved music very much and ultimately became a musician. Actually, life doesn't work in a particular way. We go through different situations in our daily life and all our decisions are based on those situations.
The guy who became a musician but couldn't study well, according to his parents, could have become any other normal guy doing a 9-5 job if he wilted under the parental pressure to study hard. He never regretted of neglecting his studies and carried on with his passion. People's mind may change depending on the situation and in our life, there are lots of variables. Looking back at the decisions that gave us undesirable results and repenting is a way of pulling ourselves backwards. To move ahead, we should not have regrets. What has happened cannot be reversible, so, rather than thinking about what remained a regret, remove those ifs and buts.
There is no point in thinking that this "could have happened if I took that decision at that time". You never know what could have really happened if you took that decision. Therefore, decide things keeping in mind your present situation and move ahead.